Wt  4.10.2
Release notes
Wt Release notes

Wt Release notes

This file lists important notes on migrating existing applications to newer version of Wt. It lists changes in the library that may break the way you build Wt, the way you configure Wt or the Wt API and behaviour.

Release 4.10.2 (November 8, 2023)

Wt 4.10.2 is a patch release that addresses the following issues:

  • Issue #11932: when calling WPushButton::setMenu after a WPopupMenu had already been added, the second menu wasn't added to the button, and both WPopupMenus were removed. Now, the new WPopupMenu is correctly added to the button.
  • Issue #11974: when dynamically making a field visible in FormView the form would only show the label and not the corresponding widget. This has now been corrected by having FormView override createFormWidget.
  • Issue #11984: corrected WTableView's drag & drop functionality. When a WAbstractItemModel's items have the flags for drag & drop enabled (found in ItemFlag), the WAbstractItemView has setDragEnabled(true) and setEnabledDropLocations() set to DropLocation::BetweenRows, the view will now correctly drop the items at the location indicated by the cursor, and will no longer cause an issue when moving the cursor out of the table when dragging.
  • Issue #11890: if a user were to delete a WPopupWidget, which they can do as detailed in the documentation, they would encounter a use-after-free. This has been corrected, so that the content of a WPopupWidget can be removed when being hidden.
  • Issue #11985: ensures that if a WStringListModel is used in a WTableView that allows drag & drop, the content of the model is correctly updated.
  • Issue #12012: due to an oversight in Issue #10512, the keyboard and mouse events for a WTreeView's node were missing.
  • Issue #11882: the fieldset element, used by WGroupBox has been corrected when using Bootstrap 5. A default HTML value was used here, which caused the content to not be rendered correctly.
  • Issue #12006 a JavaScript error could occur if no semicolon was added to the JS code when called by setJavaScriptMember or callJavaScript.
  • Issue #11897: fixed a log that was not configurable. The response to a HTTP request was always logged (like GET /path contentlength). All logs should be configurable, hence it is now logged under info:wthttp.
  • Issue #11959: the GetOnePixel deprecation warning from GraphicsMagick was removed.
  • Issue #7196: remove a deprecated Pango call. If you compile with Pango enabled, you will no longer see the warning that pango_fc_font_(un)lock_face is deprecated.

Release 4.10.1 (September 20, 2023)

Wt 4.10.1 is a patch release that addresses the following issues:

  • Issue #10512: ensures that the disabled state of any WWebWidget or WCompositeWidget is correctly propagated to its children. Before, if a user set a widget as disabled that contained children like a WMenu, a new WMenuItem could be added, that was enabled. For some of the affected widgets, this meant that the new item could not be selected, since the signal was not exposed, but in some cases, like with a WMenu this was still possible. The disabled state of a widget now propagates to its children so that a disabled state can be set consistently for a parent. This doesn't actually set setDisabled() of the children. This state can be set separately to manage the child's disabled state without regard to its parent.
  • Issue #11804: the WEmailValidator was corrected. There was a missing case in the client side regex that did not allow a hyphen in the domain of an email address. The server side regex was correct, but nevertheless the case has been added to the tests.
  • Issue #7645: a WAnchor loaded through JavaScript, with progressive bootstrap will correctly add an empty "href" attribute. This allows the item to be selected on the page by pressing the Tab button, allowing keyboard navigation.
  • Issue #11848: this corrects an edge-case in WSuggestionPopup where forcibly displaying the pop-up via C++ code would cause it to be unfiltered.
  • This is a combination of Issue #9595 and Issue #9596: where the Postgres backend will again rely on standard library functionality (which was substituted in Issue #9490 for boost::spirit). This implementation, however, caused the loss of some precision with floats and doubles. The conversion from and to string now happens with the standard library charconv, which is available in C++17 (or in C++14 as an extension). In case this library is not available, Wt will fall back to std::stof and std::stoi, but will still use boost::spirit in case of subnormals (which would result in an out_of_range exception).
  • Issue #11769: The MySQL backend will now correctly catch the ER_CLIENT_INTERACTION_TIMEOUT error.
  • Issue #11302: when closing a HTTP socket, it was possible that the server just started handling a TCP/SSL request. This resulted in a free-after-use for the listener. The listener is now first checked, so we do not get this race condition.
  • Issue #11408: fixed several concurrency issues in the wthttp library.
  • Issue #11852: the Message's date header was corrected. In case that a localized abbreviation was defined for the month or day, this string was placed in the header. Some providers / exchanges may reject these emails, since they follow RFC-5322 (see here) and expect English names.

Release 4.10.0 (May 30, 2023)

Wt 4.10.0 mainly features back-end improvements and some new features that provide some convenience. There were some issues with persisting dates and time in Sqlite3.

In some cases user will have to change some things about their CMake set-up: If users wish to use OpenGL, they may need to provide a GLEW installation with GLEW_ROOT, since GLEW is no longer bundled with Wt.

New features

  • Issue #7279: added WEmailEdit and WEmailValidator, implementing a <input type="email">.
  • Issue #8760: extended Auth::AuthWidget with the option to resend verificiation emails. When email verification is configured to be required and the email somehow got lost, the user would be stuck not being able to log in. When the user tries to log in now, an info message will be shown saying they need to verify their email first along with a new button to resend the verification email. The user must then enter the email address again in a dialog before the email is sent.
    The virtual methods AuthWidget::letResendEmailVerification() and AuthWidget::createResendEmailVerificationView() can be used to customize the UI.
  • Issue #7814: The SameSite attribute of the Set-Cookie HTTP header is now rendered by Wt. To avoid adding yet another parameter to the WApplication::setCookie() method, the class Http::Cookie was introduced that allows configuring all cookie attributes using setters. Objects of this type can be passed to the new setCookie() and removeCookie() methods in WApplication.

Other improvements

  • Issue #11384: it was possible for Mail::Client::connect() to throw an exception if the DNS resolver failed to resolve the SMTP server's hostname. We changed this to log an error and return false instead (as indicated by its documentation). Mail::Client::send() could cause a null pointer to be dereferenced, either because a TLS connection was attempted while Wt was built without OpenSSL, or because the user did not call Mail::Client::connect() first. send() was fixed to log an error and return false instead.
  • WServer::addResource() can now take a shared_ptr instead of a raw pointer, enforcing that the resource lives at least as long as the server, unless removed with WServer::removeEntryPoint(). The overload that takes a raw pointer is now deprecated. This also fixes issue #11301, where there could be a use-after-free in test.http.
  • Issue #11412: shift-click to open a new window did not work for links to internal paths. Shift-click is now handled by the browser, like ctrl- and meta-click.
  • Issue #11604: added a virtual destructor to WAbstractFormDelegate to ensure proper deletion and explicitly removed the copy and move constructor and assignment operator.
  • Issue #11562: The tutorials (Wt, Dbo, and Auth) were updated to be built with Asciidoctor instead of the legacy Python implementation, its style was updated to match the JWt website style, and the text was brought up to date a bit. The blog example was likewise updated to use Asciidoctor.
  • Issue #11210: WTable::headerCount() has been made const.
  • The obsolete CMake options ENABLE_EXT, WT_NO_STD_LOCALE and WT_NO_STD_WSTRING were removed.

Bug fixes

  • Issue #11426: Sqlite3: fixed multiple issues with dates and timestamps:
    • Timestamps before 1970 would not be saved properly on Windows, because of limitations of the gmtime function on Windows. The new implementation uses the date library instead.
    • There was a bug in the conversion to a date time string if ISO8601AsText was set as the date time storage. For timestamps before 1970 the millisecond part would be saved as a negative integer, e.g. December 31, 1969 23:59:59.999 would be saved as 1970-01-01T00:00:00.0-1 instead of 1969-12-31T23:59:59.999.
    • There was a bug in the conversion to and from Julian days if JulianDaysAsReal was set as the date time storage. The decimal part was divided by 1000, and it was ahead by 12 hours due to it using midnight rather than noon 1 January 4713 BCE as the reference timestamp. It is now consistent with SQLite's own julianday() function.
    • There was a bug in the conversion to UNIX timestamps if UnixTimeAsInteger was set as the date time storage. The date part was discarded, and the time was saved as a number of milliseconds instead of seconds.
  • Issue #11578: fixed an issue with the Dbo forms not correctly validating invalid WDate and WTime values causing the forms to clear the values. Now the forms will give a validation error and prompt the user to correct it before saving the form.
  • Issue #11377: when using wtisapi with WebSockets enabled in the wt_config.xml, Wt would try and fail to establish a WebSockets connection (this is not supported by ISAPI). Wt now disables WebSockets (and notifies this in the logs) when using ISAPI.
  • Issue #11423: WResource::internalPath() now returns the empty string for static resources, since it doesn't make sense for static resources.
  • Issue #10485: fixed an issue where Wt would not build on Apple platforms with ENABLE_OPENGL=ON. This changes the CMake setup, so that we now rely on built-in FindOpenGL and FindGLEW modules. As a consequence, the bundled GLEW installation was removed. This means that a GLEW installation will need to be provided when building Wt from source. CMake will find GLEW if it is installed in a standard location. The GLEW_ROOT CMake variable can be used if it is installed elsewhere.
  • Issue #11376: fixed an issue with redirects when using wtfcgi.

Release 4.9.2 (April 18, 2023)

Wt 4.9.2 is a patch release that addresses the following issues:

Release 4.9.1 (January 20, 2023)

Wt 4.9.1 is a patch release that addresses the following issues:

Release 4.9.0 (December 22, 2022)

Wt 4.9.0 features a lot of changes under the hood: we have painstakingly removed jQuery from Wt, modernized the JavaScript, and added a linter, formatter, and a new minifier in the process.

A more directly noticeable change is the fact that we gave the documentation a new lick of paint using the Doxygen Awesome theme. Also, now that we added some tooling to customize WBootstrap5Theme, the widget gallery's primary color was updated to be more in line with Wt's website.

Backwards incompatible changes

Removal of jQuery

We removed every use of jQuery from Wt, and jQuery is now no longer automatically loaded. This means that if you relied on the included jQuery version (for example, the $ object or function), you will have to make some changes to make it work with Wt 4.9.0. There are several options:

  • Replace your uses of jQuery with vanilla JavaScript, which is what we did.

    For example, the $ function can often be replaced with querySelector or querySelectorAll.

  • Load jQuery yourself using WApplication::require(). WApplication::requireJQuery() has been marked as deprecated.

    For example: application->require("https://code.jquery.com/jquery-3.6.1.slim.min.js", "$");.

  • Change your wt_config.xml, adding a <head-matter> section that loads jQuery through a <script> tag:


Changes to WBootstrap5Theme

Collapsible panels
WBootstrap5Theme has used an accordion instead of a card for collapsible panels since its introduction in Wt 4.6.0. Now, WPanel always uses a card. This allows all panels to have a consistent appearance, regardless of whether they can be collapsed or not. Additionally, the WPanel::collapse() and WPanel::expand() functions will now work as expected with WBootstrap5Theme. This change resolves issue #10364.
Bootstrap 5 theme customization
We've made it easier to customize the Bootstrap 5 theme. WBootstrap5Theme now loads a single CSS file that is built from Sass source files. The custom-bs-theme example shows how this allows the theme to be customized. The widget gallery makes use of this by changing the primary color from Bootstrap's blue to the purple used in Wt's logo and homepage. This change resolves issue #9350.

New features

Other improvements

  • Issue #11067: animateShow() and animateHide() were overhauled to use the Web Animations API. This fixes issues with choppy animations.
  • Issue #8629: In order to ease maintenance, and make contributing to Wt easier, we changed the JavaScript minifier from the old version of Google Closure compiler we were using to terser.
  • Issue #10966: Added a JavaScript formatter to format Wt's JavaScript code. Its usage is detailed in the Wt source tree at doc/development/javascript.md.
  • We gave our reference documentation a new lick of paint: we're now using the Doxygen Awesome theme, which also has a dark mode.
  • Whereas trying to construct UpdateLock with a null WApplication pointer would cause a null pointer dereference before, it now simply yields an unsuccessful UpdateLock (PR #195 by Steven Köhler).
  • Issue #10395: WPanel::setTitleBar(false) now automatically calls WPanel::setCollapsible(false).
  • Issue #9570: All uses of WT_CXX14 and WT_CXX14ONLY were removed in Wt's source code. WT_CXX14 is now always defined, since Wt requires C++14. We marked Wt::cpp14::make_unique as deprecated, since this only existed because C++11 lacked std::make_unique.
  • Issue #10924: The undocumented split-script configuration property was removed, simplifying Wt's internals.
  • Issue #10914: Changed some Boost.Phoenix includes to silence deprecation warnings.
  • Issue #10911: Fixed OpenSSL 3.0 deprecation warnings.
  • Issue #9252: Fixed a deprecation warning in the Pango font support implementation.

Bug fixes

  • Issue #9076: WDateEdit gave a javascript error when opening the calendar popup if the application was rendered in WidgetSet mode.
  • Issue #10488: Long polling requests interrupted on the server side now no longer prevent keep alive requests from being sent, and thus the session from timing out. This was possible when Wt is deployed behind a reverse proxy that has a shorter request timeout than the <server-push-timeout> configured in wt_config.xml.

Release 4.8.3 (December 22, 2022)

Wt 4.8.3 is a patch release that addresses the following issues:

  • Issue #11105: Wt has a built-in redirect mechanism that prevents the Referer header from showing the session id (if the session id is in the URL). This mechanism hashes the destination URL with a secret to ensure that this system is not used as an open redirect endpoint. However, in order to make dedicated session process mode work properly, this secret could be overridden by providing a Redirect-Secret header, creating an open redirect endpoint. We have renamed this header to X-Wt-Redirect-Secret to better indicate the fact that this header is nonstandard, and will only accept this header if it is coming from a trusted reverse proxy.
  • Issue #10995: fixed an issue with WContainerWidget where a session could terminate with the text "WContainerWidget: error parsing: undefined".
  • Issue #11101: fixed a data race when using dedicated session processes.
  • Issue #8093: fixed an issue where the bottom axis could be clipped off of a tall WCartesianChart (PR #178 by Apivan Tuntakurn).

Release 4.8.2 (November 4, 2022)

Wt 4.8.2 is a patch release that addresses the following issue:

  • Issue #10970: Sending an OPTIONS * request could cause an assertion failure when trying to match the request to an entry point. This could cause a crash if assertions are enabled, though they usually aren't in production builds. Since these types of requests are not properly supported by wthttp, OPTIONS * requests are now rejected.

Release 4.8.1 (September 22, 2022)

As usual, Wt 4.8.1 is a patch release, but we also added a document clarifying our policy on which minimum versions of libraries Wt requires (issue #8801). You can find this document in Wt's source tree at doc/MinimumDependencyVersions.md.

That aside, Wt 4.8.1 addresses the following issues:

  • Issue #10909: WPdfImage: Fixed compatibility with recent libharu versions (2.4.0 and up, excluding version 2.4.1).
  • Issue #10825: Fixed an issue in WGoogleMap where some left-over JavaScript code in setMapTypeControl targeting the v2 API would cause a JavaScript error.
  • Issue #10834: Fixed a regression since Wt 4.8.0 with the tests for issue #9442, dbo_test46 would fail with the MySQL/MariaDB and the SQL Server backends because they sort null values differently from PostgreSQL.

Release 4.8.0 (July 8, 2022)

Wt 4.8.0 doesn't come with any big new features, but it does include some handy new functions here and there, and some improvements. We have also removed Skia from Wt because we can use Direct2D on Windows and GraphicsMagick on every other operating system.


  • Issue #10254: The Skia-based WRasterImage implementation has been removed, since it was unmaintained and dependent on very specific Skia versions, and we have good alternatives with GraphicsMagick and Direct2D.

Changes in default behavior

  • Notable changes in exception handling:
    • Issue #10137: Exceptions thrown from WResource::handleRequest() are now caught and logged instead of causing a crash.
    • Issue #10136: Uncaught exceptions emanating from WApplication::notify() would be sent to the browser. This exposes potentially sensitive details about the application to the end user. Wt now just sends a simple "500 Internal Server Error" without any further details. The exception details will still be logged.
  • Issue #8660: The default value of OAuthService::popupEnabled() was changed from true to false. This means that the default method when using OAuth is always to redirect instead of using a popup.

New features


  • Issue #10019: Added a cleaner fix for issue #9922. Instead of discarding responses containing only {}, Wt now no longer delineates its JavaScript with curly brackets.
  • PR #192: Removed obsolete cursor: hand

Bug fixes

  • Issue #9938: The close icon for a WDialog was displayed on the left side of the title bar when using bootstrap 5. This was fixed by using the Bootstrap 5 appropriate <button> with the btn-close style class. A new Wt.WDialog.titlebar template was introduced so that the rendering of the title bar can be overridden.
  • Fixed issue #10599: there were issues on macOS when using a statically built Wt library, causing the linker to output warnings and some test cases to fail.
  • Fixed issue #10604: self-assignment of Wt::Dbo::Query would lose bound parameters.
  • PR #187: Negative floating point numbers would always be formatted in scientific notation when being output as JavaScript. This has been fixed to only use scientific notation for particularly small or particularly large numbers.


  • Issue #10248: Tabs have been replaced by spaces in the source code. Previously, we had a mix of tabs and spaces, where newer code used only spaces, and older code changed 8 spaces into a tab.

Release 4.7.3 (July 8, 2022)

Wt 4.7.3 is a patch release that addresses the following issues:

Release 4.7.2 (May 12, 2022)

Wt 4.7.2 is a patch release that addresses the following issues:

  • Issue #10287: wthttp now properly sends close frame back when WebSocket connections are closed. Previously, the browser would send a close frame and not get a response back. On Firefox, these kinds of errors caused the creation of new WebSocket connections to the same endpoint to be delayed by up to one minute, making it seem like the application is hanging.
  • Issue #10003: Calling WApplication::refresh() in the application constructor (e.g. by setting the locale) would produce a JavaScript error if there was a WSpinBox in the widget tree.
  • Issue #10320: Version 4.5.2 (issue #9363) and 4.6.2 (issue #9572) added workarounds to deal with the incorrect formatting of floating point numbers with Boost since version 1.76.0. Since Boost 1.79.0 this issue has been fixed, so the workaround is now disabled for versions since 1.79.0.

Release 4.7.1 (April 15, 2022)

Wt 4.7.1 is a patch release that addresses the following issues:

  • Issue #9922: Wt would send an update to the browser on every call to WApplication::triggerUpdate() if server push was enabled. This is because Wt thought the state was dirty when its JavaScript response buffer contained only {} (empty block). This has been fixed by not sending a response if the buffer contains only {}.
  • Issue #10177: WT_API was missing from Json::TypeException, which meant that its symbols were not exported from dynamic libraries.
  • Issue #9695: If a WSuggestionPopup was created before the dialog it appears in, it would be displayed below the dialog. The z-index of WSuggestionPopup is now calculated using javascript so it is always shown on top.

Release 4.7.0 (March 11, 2022)

Wt 4.7.0 is a smaller release with no major new features to speak of, just some improvements and bug fixes here and there.

Notable changes in default behavior

These changes affect default behavior in Wt, and may require special attention:


  • Since Google Maps v2 is no longer available as of May 26 2021, Wt no longer supports v2.

Bug fixes

  • Issue #9562:
    • If a Mail::Message was sent more than once, the attachments would be empty after the first time.
    • Mails sent by Wt::Auth are now logged using WLogger instead of using std::cout. As a result, the logging can also be disabled by adding -info:Auth.AuthService to <log-config> in <wt_config.xml>.
  • Issue #9035: The <head-matter> configuration option did not work with <script> elements without content (e.g. when using the src attribute). The parser would always turn this into a self-closing tag, which is not allowed in HTML.
  • Issue #9271: Dbo::backend::MySQL now properly preserves the microsecond part of timestamps.
  • Issue #9264: Added a remark to WAbstractToggleButton::unChecked() to clarify that it is not emitted for WRadioButtons.

Release 4.6.3 (March 10, 2022)

Wt 4.6.3 is a patch release that addresses the following issues:

Release 4.6.2 (February 15, 2022)

Wt 4.6.2 is a patch release that addresses the following issues:

  • Issue #9424: The special "no selection" status of WComboBox was lost if the items were rerendered, e.g. if the model changed.
  • Issue #9721: Somewhere during the Bootstrap 5 transition, we accidentally removed some example code (pdfImageWrite.cpp) from the widget gallery. We added it back.
  • Issue #9572: Some JSON serialization tests were temporarily disabled since Boost 1.76.0, since the workaround put in place does not generate entirely the same result.
  • Issue #9571: Provided a fix for a false positive -Wfree-nonheap-object warning in Wt::Signals.

Release 4.6.1 (December 23, 2021)

Wt 4.6.1 is a single bug fix release, fixing a regression (issue #9523). A potential null pointer dereference would crash the Wt site or widget gallery every few days.

Release 4.6.0 (December 14, 2021)

We know that this one took a bit longer than normal. Starting now we intend to make the Wt release cycle more regular, with a release every three months, so we're planning to release Wt 4.7.0 in March 2022. We've still been busy improving Wt though. Wt 4.6.0 introduces some major new features, including Bootstrap 5 theming support, Dbo-based forms, and SAML support for Wt::Auth.

Bootstrap 5 theming support (issue #7418)

We split up WBootstrapTheme into WBootstrap2Theme and WBootstrap3Theme, and added WBootstrap5Theme. We found that the different Bootstrap versions were distinct enough to warrant splitting each version of the theme up into its own class.

We abandoned development of WBootstrap4Theme, since there were still some unsolved issues with it, and we didn't expect many users to be interested in it.

We also updated the design of the widget gallery. It now uses Bootstrap 5, and no longer uses box layouts, instead opting for a more responsive design featuring a collapsible menu on narrow screens. This means that the widget gallery is finally usable on mobile phones!

Dbo-based forms (issue #8622)

We added a new feature that allows Wt to automatically generate a form for a Dbo class. Based on the data types that are used by the Dbo class, Wt will generate form delegates. These form delegates are responsible for creating the widget and optional validator for representing the data type in the UI. For example: WString objects are by default represented by a WLineEdit, WDate objects by WDateEdit, and so on.

The user is able to override the default behavior either by customizing the widgets and/or validators or by creating a new form delegate for the specific field and adding it to the form.

All classes related to this new feature have been added to a new Wt::Form namespace. Here's a short overview of the most important classes within that namespace:

  • FormModel: a model class that holds the data of the database object.
  • FormView: a view class to represent the database object in the UI.
  • WAbstractFormDelegate: delegate for creating form widgets.

We also added a new example to display this new functionality.

SAML support for Wt::Auth (issue #8621)

We added SAML support for authentication with third party identity providers. Wt::Auth::Saml::Service implements a minimal SAML 2.0 service provider for single sign on.

We added a SAML feature example to demonstrate this.

Note: this implementation is based on Shibboleth's OpenSAML library. This library uses the Apache License Version 2.0. Due to incompatibility with the GNU General Public License V2.0 used by Wt, a commercial Wt license is required to distribute derived works using SAML authentication.

Other features and improvements

  • It is now possible to suspend the WApplication using the suspend function. Previously, logging in using an external authentication provider required a popup, but this can now be done through a redirect (OAuthService::setPopupEnabled() and Saml::Service::setPopupEnabled()). This can also be useful for redirecting to payment providers. (See issue #7742 and issue #9439.)
  • Added WServer::docRoot(), which allows access to the --docroot argument of wthttp. (See issue #9391.)
  • The Bootstrap themes now no longer need an active WApplication upon construction to properly function, through the addition of an init() function. (See issue #9204.)
  • The WAbstractItemView now allows drag/drop in between rows. See setEnabledDropLocations(). (See issue #8636.)
  • With the latest version of Visual Studio supporting std::chrono's date and time zone support it is now possible to use it when building Wt in C++20 mode (-DCMAKE_CXX_STANDARD=20 -DWT_CPP20_DATE_TZ_IMPLEMENTATION=std). This means that when Wt is compiled this way time zone support just works on Windows like it already did on Linux, instead of requiring you to download the IANA time zone database. (See issue #8595.)
  • Updated the date library to commit fb2554a7e00b24d23838b57a4db4121e148edb5c.
  • Ability to change the row header count of WTableView after it is rendered (see issue #8077).
  • Splitting up updates to stay under the form data limit when many updates are rapidly generated (issue #7990).
  • Revert delay of WWidget::load(). Load now happens when a widget is added to the widget tree. (See issue #7968.)
  • Added option to not automatically select first suggestion of a WSuggestionPopup.
  • Wt::Http::Request::hostName() now takes into account X-Forwarded-Host.
  • Updated the version of the included SQLite to version 3.35.5.
  • Added doc/licenses.md as an exhaustive list of the licenses used by Wt, source code from external sources included in Wt and any external dependencies.

Bug fixes

Release 4.5.2 (December 14, 2021)

Wt 4.5.2 is a bugfix release containing the following changes:

  • Issue #9490: Fixed a possible exception being thrown in the Postgres backend for Dbo when subnormal floating point numbers are retrieved from the database.
  • Issue #9414: Fixed an error that occurred when trying to link libwtdbosqlite3 on Fedora 35.
  • Issue #9363: Added a workaround for Boost Spirit issue #688, affecting versions of Boost ≥ 1.66.0.
  • Issue #9270: Fixed a possible but very rarely occurring race condition in the generation of ids that would make it possible to have two widgets with the same id in the same WApplication.
  • Issue #9230: Fixed an issue where the 3-argument version of QueryModel::setHeaderData was no longer accessible.

Release 4.5.1 (October 7, 2021)

Wt 4.5.1 is a bugfix release containing the following changes:

Release 4.5.0 (December 15, 2020)

Notable changes

  • Wt now targets C++14, and CMAKE_CXX_STANDARD defaults to "14". There appears to be no good reason to maintain C++11 support, since every compiler that supports enough C++11 for Wt also supports enough C++14. You should still be able to use C++11 mode when using Wt as a library, but Wt itself no longer builds in C++11 mode.
  • Wt::Dbo: the Firebird backend has been marked as unmaintained. The Firebird tests were not succeeding, likely because of an incompatibility with the unmaintained IBPP that the Firebird backend is based on and recent versions of Firebird.

Features and improvements

  • Issue #7586: The <behind-reverse-proxy> option has been deprecated in favor of a new <trusted-proxy-config> option. It's now possible to specify the IP header that Wt should look for using <remote-ip-header> (defaults to X-Forwarded-For). Wt will trust all proxies listed in <trusted-proxies>. When <behind-reverse-proxy> is set to true, the behavior stays the same as it was before. See the library overview for more information about this option.
  • WFormModel now uses string comparison instead of pointer comparison for its fields.
  • Issue #7666: In some cases Wt 4.4.0 would connect jsScrollVisibilityChanged even if it was not actually being used, causing extra unnecessary requests.
  • Added Jenkins pipelines in the jenkins folder. We use Jenkins to test Wt at Emweb but we would usually keep this configuration in Jenkins. Our pipelines for Linux and FreeBSD have now been updated a bit and moved into the Wt repository, since they may be of use to people looking to contribute to Wt.
  • Issue #7669: Wt now automatically uses addChild instead of addWidget when addNew is used on a global widget, like WPopupWidget.

Bug fixes

  • Issue #6367: fixed issue where wthttp would no longer accept new connections when an error occurred while accepting a connection, e.g. if the open file limit was reached.
  • WDate::currentServerDate() and WTime::currentServerTime() now correctly return the local date and time on the server instead of UTC.
  • Fixed visibility of OAuthProcess and OAuthAccessToken.
  • Fixed issues #6548 and #7749: URL parameters were being parsed more than once for file uploads, causing a rapid accumulation of duplicate values during uploads, and potentially causing segmentation faults. The wtwithqt example was also updated so that it properly waits for condition variables in a loop, to deal with spurious wakeups. Also fixed a potential use-after-free when updating resource progress.
  • Fixed an issue where the HTTP Client would wait indefinitely for data when Content-Length is zero.
  • WebSockets: If a bad value for server_max_window_bits or client_max_window_bits was encountered, this would cause an uncaught exception and a crash. This is now handled properly.
  • Fixed issue with DISTINCT ON in X3 based query parser: the fields listed there would incorrectly be regarded as fields being returned.
  • Fixed issue #7677: when a font could not be loaded in WPdfImage, this would throw an uncaught exception. This was changed to logging an error.
  • Fixed issue #7719: Wt::asString did not properly handle unsigned long.
  • PR #166: fixed mandelbrot example: missing call to done().
  • PR #167: we need to link with Boost unit_test_framework on Windows when BOOST_DYNAMIC is ON.
  • Fixed an issue where WMediaPlayer would not get properly loaded when reload-is-new-session is false, and the page is refreshed.

Release 4.4.0 (August 3, 2020)

Wt 4.4.0 adds a couple of new features, like multiple X axes, and WColorPicker, among other fixes and tweaks.

Security related

Wt now rejects GET requests for Ajax-enabled sessions that are not for resources, as an extra means to prevent session hijacking attempts. Patch provided by Bruce Toll in issue #7585.

Major new features

  • WCartesianChart: similar to how Wt 4.0.4 added support for multiple Y axes, Wt 4.4.0 adds support for multiple X axes, too. Instead of trying to squeeze another int argument into functions like WCartesianChart::map, we decided to add overloads that take two WAxis references.
  • Added WColorPicker: a simple form widget that display a browser-native color picker. Patch provided in PR #158.

Minor features

  • Wt::Dbo:
    • PR #161: added support for ON UPDATE RESTRICT and ON DELETE RESTRICT foreign key constraints in Wt::Dbo.
    • DBO_INSTANTIATE_TEMPLATES and the DBO_EXTERN_TEMPLATES macros used to be disabled with Visual Studio since they wouldn't work with old versions of Visual Studio. We reenabled those macros, since they've been working for a while now.
    • Added orWhere.
  • WFileResource: added a log message when failing to open a file. Previously, it would not be very clear why nothing was downloaded.
  • Added the MIME type for .txt files to wthttp, so that they are displayed in the browser rather than prompt a download.
  • All of the properties that Wt uses are now listed in the default wt_config.xml to make it easier to get an overview of all of them without having to find them in the reference documentation.


  • PR #162: Updated included Bootstrap 3 version to 3.4.1 (from 3.3.7)

Bug fixes

  • Wt:: Auth:
    • Issue #7518: previously, it was not possible to set AbstractStrengthValidator to non-mandatory. This has now been fixed. It now also correctly reports InvalidEmpty when the input is left empty.
    • Fixed an issue where slots connected to Login::changed() would still have the old session id, which would afterwards be updated, causing resource urls created in the slot to have the wrong session id.
  • WPaintedWidget: fixed an issue where combining incremental painting (PaintFlag::Update) with images could cause the first paint event to be discarded, resulting in an incomplete result.
  • Previously, having multiple instances of WGoogleMap could cause JavaScript errors. This has now been resolved.

Release 4.3.1 (April 20, 2020)

This release fixes the following issues:

  • WWebWidget: moved id_ out of OtherImpl: this fixes issues caused by the id_ being removed before other things that depend on it, like the jsScrollVisibilityChanged_ signal. Fixes issue #7508.
  • Fixed join information not being copied over when copying Wt::Dbo::AbstractQuery.
  • MinGW fixes: Direct2D/DirectWrite were disabled and are now enabled by default. Libraries were changed to lowercase for cross-compiling from Linux. Windows is case-insensitive, and MinGW libraries on Linux are lowercase. Fixes issue #7505.
  • Fixed a wrong documentation link in the widget gallery.

Release 4.3.0 (March 26, 2020)

Wt 4.3.0 mainly adds the ability to redirect logging to a custom logging function, and login and transport encryption to the mail client, among some other fixes and tweaks.

Logging redirection (issue #7240)

Before, it was possible to send logging to a file or an std::ostream, and configure which messages were logged in wt_config.xml. Wt 4.3.0 extends this with the ability to send all logging to a function, allowing users to redirect Wt's logs to whatever logging framework they prefer to use.

The few log messages coming from Wt::Dbo would always be logged to std::cerr. It is now possible to change this to use Wt's logger, or a custom log function.

To allow for this new functionality, we introduced an abstract WLogSink class, and the following functions:

Mail client: support for login and encryption (issue #7444)

We added basic support for PLAIN and LOGIN authentication methods, and encryption using StartTLS or just simple TLS.

You can enable authentication with Client::enableAuthentication(), and encryption with Client::setTransportEncryption(), or using the configuration properties smtp-auth-username, smtp-auth-password, smtp-auth-method, and smtp-transport-encryption.

Other changes

Some small changes in behaviour that you may want to be aware of:

  • Wt::Auth: lost password tokens used to be removed as soon as the link was used, even when they were not actually used to change the password. Now, the token will stay valid until the password is actually changed. Also, if the password is changed through other means, the update password token is invalidated.
  • WCanvasPaintDevice: instead of stopping the drawing entirely when drawImage() fails (e.g. because of a missing image), the image will be skipped but drawing will continue. An error will be logged to the console.
  • Issue #7060: fixed Request::clientAddress() when behind a reverse proxy to be the same as WEnvironment::clientAddress(), and as mentioned in the documentation.
  • Issue #7404: reparenting of popup widgets should only stop at scroll bars.

Other changes and fixes:

Release 4.2.2 (March 16, 2020)

This release fixes the following issues:

  • Security-related: in Wt::Auth the lost password email would be sent to the email address provided in the form, rather than the user's configured email address. While we treat email addresses as case insensitive, it is possible that the mail server may not, and that could potentially be used to steal an account. It is however quite rare for email services to be case sensitive.
  • Issue #7439: ensure that tooltips are always on top, even inside of a dialog.
  • Issue #7448: fixed compilation error on recent versions of MinGW, by using the gmtime_s function on Windows.
  • Issue #7447: fixed text format being reset when the text of a WAnchor is cleared.
  • Fix for WLeafletMap issue that was reported on the forum: signals would get unexposed when options were changed.
  • Issue #7457: moved call to WApplication::require() to the constructor, since calling it in the render function may cause issues.
  • Fixes for WVirtualImage:
    • Do not render zero width or zero height images. This was possible when imageWidth or imageHeight was a multiple of the gridImageSize.
    • Fixed scrollTo() when the image is narrower than the viewport: scrollTo(0, 0) would not put (0, 0) at the top left when the image was narrower (or taller) than the viewport.
  • Issue #7480: prefix Wt's crypt functions to fix issues when linking with libxcrypt, and also set C code's default visibility to hidden.
  • Issue #7468: fixed panning not working properly for a WCartesianChart with plain tooltips.
  • Issue #7482: lastId_ in Postgres backend should be long long.
  • Issue #6774: misc. WTreeView fixes.
  • Fixed use after free caused by order of destruction in WWebWidget destructor.

Release 4.2.1 (February 6, 2020)

This release fixes the following issues:

  • wthttp fixes:
    • Issue #7406: requests for absolute-form URLs (e.g. GET http://localhost:8080/ HTTP/1.1 instead of GET / HTTP/1.1) are now rejected. No client normally sends requests like this to an origin server. See RFC 7230, section 5.3.2.
    • Issue #7405: multiline HTTP headers (line folding) were causing wthttp to segfault. This was fixed by removing support for (obsolete) line folding. See RFC 7230, section 3.2.4.
    • Issue #7390: added MIME type for .wasm files.
    • Issue #7384: setting the --docroot of wthttp to .; will now correctly make it so that no path is interpreted as being a static resource.
  • Issue #7350: fixed WPaintedWidget's wtResize JavaScript to assume its preferred size when called with a size of -1.
  • Fixed possible JavaScript errors caused by WContainerWidget's wtEncodeValue JavaScript not being terminated by a semicolon.
  • Issue #7407: fixed JavaScript memory leak related to deferred or HTML tooltips.
  • Issue #7360: documented Wt::Mail::Message::Recipient.
  • Issue #7393: if the internal path is set to invalid in initialize, Wt should still send a 404 status code.
  • Issue #7361: a previous attempt at fixing horizontal scrolling stutter in Wt 4.1.1 caused a regression in WTableView::scrollTo().
  • Fixed several issues with WLeafletMap that were reported on the forum.
  • WCartesianChart: when there were so many bars on a bar chart that the width of a bar became 0, placing tooltips would cause a crash. Wt will now skip tooltip placement when bars get too narrow.
  • WSuggestionPopup: when setDropDownIconUnfiltered(true) was used, pressing the up/down arrows to move through the list would cause it to be filtered.
  • Reverted a previous change to WModelIndex: since the comparison operator of model indexes uses the parent, we can't insert raw indexes into a std::set.
  • Issue #7353: added mention in 3.5.0 release notes about WPdfImage pen width fix.
  • registerType now uses std::type_index instead of comparing type_info pointers.
  • Some widgets (like WTreeView) would not be properly sized when they were initially hidden.
  • Fixed a segfault in WTableRow, reported on the forum.
  • Miscellaneous documentation fixes.
  • CMake fixes:
    • wt-config.cmake: CMake would look for Boost even when Wt was linked dynamically, and Boost was linked statically, like in our Windows builds.
    • wt-config-version.cmake: match function needed to be math
    • CMake needed to look for Boost::filesystem for some examples (but didn't).

If you diff this release with the last one, it looks like we've changed a lot more, but this is simply because we needed to update Emweb bvba to Emweb bv everywhere.

Release 4.2.0 (December 3, 2019)

Wt 4.2.0 introduces no major new features, but comes with some nice fixes and little quality of life improvements.

Notable backwards-incompatible changes

  • WSuggestionPopup: wordSeparators no longer requires (extra) escaping, so a newline is indicated with the string literal "\n", not "\\n". Similarly, the whitespace property was incorrectly documented as requiring (extra) escaping.
  • The WLogEntry copy constructor–which logically performed a move–was removed and replaced by a move constructor.
  • Removed WDatePicker::setGlobalPopup–it was deprecated in Wt 3.3.0, but we forgot to remove it in Wt 4.
  • WLogger now logs opening of log file to the previous output (usually std::cerr) using the logger instead of directly to std::cerr. This allows to disable this log message with -info:WLogger.

CMake changes

  • When using GCC and clang, the default visibility of symbols is now set to hidden. This limits the exported symbols to only Wt's public interfaces, reducing the size of .so files and preventing accidental use of unexposed APIs.
  • Added Wt version information to Wt's CMake config files

HTTP connector

It's now possible to get client certificate information in wthttp when behind a reverse proxy, see the documentation for WEnvironment::sslInfo() for more information.

This is tested to work with nginx and Apache. HAProxy is currently not supported, since its variables are in a rather different format.

Wt can still use this info even if Wt itself is compiled without OpenSSL.



  • Limited prevention of default action of the dragstart event to only draggable widgets. This used to be global (set on document.body), but could conflict with other JavaScript libraries, especially when Wt is used in WidgetSet mode.
  • Issue #7210: fixed removal of all widgets in a layout causing a JavaScript error
  • Fix for PR #145: fixed linking error on Windows (unresolved external symbol "public: static struct Wt::NoClass Wt::NoClass::none")
  • WPainter: fixed arc drawing code to be consistent across different backends, and with Qt's QPainter. Its behavior used to be erratic when angles larger than 360 degrees or lower than 0 were used.
  • WPdfImage: fixed double scaling of pen width (e.g. a pen of width 4 pixels, and a scaling factor of 2 would result in a 16 pixel wide pen instead of an 8 pixel wide pen).
  • Many documentation tweaks and fixes that were discovered when working on JWt 4.
  • Fixed issue #7139: some widgets would fail to be correctly reparented.
  • Fixed issue #7336: Wt was touching the history API every 10 ms when scrolling to store the scroll position, causing sluggishness, especially on mobile browsers with smooth scrolling. The scroll position is now saved after the user has stopped scrolling.
  • Fixed issue #7323: updated the broadcast feature example: its use of bindSafe() was incorrect

Release 4.1.2 (October 30, 2019)

This release fixes the following issues:

  • wthttp security issues:
    • Wt internally used an SSL-Client-Certificates header to send client certificates to child processes when using dedicated process mode. It was however always accepted even when Wt was not behind a reverse proxy, and sent to child processes as-is. wthttp now correctly disregards it when not received from a reverse proxy. The header was also renamed to X-Wt-Ssl-Client-Certificates to clarify that it is a non-standard internal Wt header.
    • When using dedicated session processes with wthttp, the parent process would trust X-Forwarded-Proto and X-Forwarded-Port even when Wt was not configured to be behind a reverse proxy. These are now discarded.
  • Fixed an issue raised on the forum causing WTreeView to not properly react to certain size changes.
  • Fixed issue #7291: wtfcgi would not properly match default entry point
  • Fixed a few issues found by clang-analyzer:
    • Fixed an issue in WAnchor that would cause image() to return nullptr if it was provided in the constructor.
    • Fixed WCssDecorationStyle self-assignment
  • Made tests succeed even if Wt is built with ENABLE_UNWIND=ON.
  • issue #7292: OAuthService now correctly uses refresh_token instead of refreshToken
  • Http::Client fixes:
    • fixed issue #7272: support @ character in the path of a URL
    • fixed 204 No Content response code behavior (would hang before, waiting for content) (issue #7273)
  • More informative error and exception messages:
    • QueryModel's "geometry inconsistent with database" exception now contains row and cache start and size information
    • WebSession's "not serving this" info message contains more context so it's less confusing
  • Documentation fixes:
    • The release notes for Wt 3.3.8 incorrectly referred to allowed-hosts, while this property is actually named allowed-origins
    • Updated WLocale::setTimeZone() documentation

Release 4.1.1 (September 9, 2019)

This release fixes the following issues:

  • Fixed horizontal scrolling stutter on mobile browsers in WTableView
  • Fixed issue #7000: possible out of bounds access in WTableView::itemWidget()
  • Fixed valueChanged() documentation of WSpinBox and WDoubleSpinBox
  • Fixed issue #7164: Added missing <stdexcept> include to observing_ptr_impl.hpp
  • Fixed issue #7167: configure SSL context when using --https-listen too (not just when using --https-address/--https-port
  • Fixed issue #7187: contents of WTabWidget did not properly stretch in height
  • Fixed issue #7193: compatibility with Pango 1.44: added harfbuzz include dir
  • Fixed issue #7195: contents of WStackedWidget would not properly respond to window size change
  • Fixed issue #7206: added mention in Wt 4.0.0 release notes that setObjectName() does not change a widget's id anymore. It is now in an extra attribute called data-object-name.

Release 4.1.0 (July 31, 2019)

This is the first release to change the versioning scheme to be more aligned with semantic versioning. From now on, the last number is reserved for patches (i.e. important bug fixes), not extra features, as long as those bug fixes don't require major changes. Patches will be released up until the next minor version bump.

From now on, a 4.1-release branch will track any bug fixes, while the master branch will become the next release (in this case 4.2.0)

We won't completely ban small API-breaking changes from the minor version, but we will as always avoid them as best as we can.

This also does not mean that Wt will now have a stable ABI. You will always have to recompile in order to do a minor version upgrade of Wt. Wt has never had a stable ABI, and that isn't going to change.

Apart from that, this release features one new widget (WLeafletMap) and many little tweaks, features, and bug fixes.

Notable backwards-incompatible changes

  • Extensionless headers (e.g. #include <Wt/WApplication> instead of #include <Wt/WApplication.h>) have been deprecated since Wt 4.0.0. These headers were now removed. Use the script migrate/wt4_add_h_to_includes.py if you want to automate the rewriting of extensionless headers.
  • When using the GraphicsMagick implementation of WRasterImage, the rendering to raster image is now done in done() instead of handleRequest(). You were always supposed to destroy your instance of WPainter, or call WPainter::end() before e.g. using write(), but Wt used to be rather forgiving—it would just work. If you are getting empty images after updating, this would likely be the reason.
  • WApplication::UpdateLock::operator bool() and observing_ptr::operator bool() were made explicit, so they will no longer implicitly convert to bool, only contextually. This may cause some valid code to no longer compile, but it is more likely that it will actually uncover bugs.
  • The default z-index of WPopupWidget was changed to 1100 instead of 100, since 1000 is the highest z-index used by Leaflet. This is generally considered an implementation detail, but if you have written any custom CSS that sets the z-index, then you may have to update this CSS.

New widgets

  • WLeafletMap: this is a wrapper around the Leaflet JavaScript library. It has support for some basic features of Leaflet, and one special feature: the ability to add arbitrary widgets (within reason) as markers to the map using WidgetMarker.

New examples

CMake changes

  • Wt now uses CMake's included FindOpenSSL, FindZLIB and FindPNG modules instead of its own.
  • WT_CPP17_ANY_IMPLEMENTATION is now set to any by default when CMAKE_CXX_STANDARD is set to 17 or higher, i.e. it defaults to std::any.
  • Removed the "vintage" method of finding Boost, because it has been obsolete for a long time already.
  • Fixed building with Boost 1.70 when using Boost's included package configuration files for CMake.
  • Made the wtwithqt example build with Qt 5 too, not just with Qt 4.
  • Made sure we can properly build wtdbomysql with a static MariaDB client library on Windows.


  • Added AuthService::setAuthTokenUpdateEnabled(). Previously, when using the remember me functionality the auth token (remember me cookie) would be changed. When accessing the application from two tabs at the same time, however, or when refreshing quickly, this could cause the session to be logged out: the auth token has changed, but the client still uses the old one. This is still the default behavior, but you can disable it by using setAuthTokenUpdateEnabled(false).
  • Fixed a use-after-free issue when Auth::Login::changed() is connected to a slot that removes the AuthWidget.


  • Added AbstractQuery, an abstract base class of Query, to facilitate the dynamic generation of queries.
  • Added Query::join(), Query::leftJoin(), and Query::rightJoin().
  • Added support for std::optional when using C++ ≥ 17.
  • std::chrono::time_point and std::chrono::duration were treated as nullable, while they should be non-nullable, since they have no reasonable "null" value. Use std::optional or boost::optional to make them nullable instead.
  • Fixed a query corruption bug when using UNION, INTERSECT, or EXCEPT (issue #7028).
  • Fixed a crash when using Session::dropTables() while there is an active transaction, as reported on the forum.
  • PostgreSQL uses ? for some operators, but that is also the character we use for placeholders in prepared statements. If the literal ? is meant instead of a placeholder, you can now use ??. This is similar to how PostgreSQL's JDBC driver handles it.

Miscellaneous features

Miscellaneous bug fixes

  • Fixed an issue where JavaScript could be sent to the browser in the wrong order when doing background updates of hidden widgets (issue #7023)
  • Fixed a client side memory leak caused by misuse of jQuery's data feature (reported on the forums)
  • WTableView: fixed row deletion behavior
  • Fixed icons not showing up on tabs and menu items when using WBootstrapTheme, as reported on the forums.
  • Fixed wrong WStackedWidget height when animating transitions (issue #6788)
  • Fixed not able to hide widgets with a flexbox-based layout (issue #6884)
  • Fixed out of bounds array access when using a widget with a custom HTML tag name (issue #7059). Widgets will now derive whether they are default inline based on the widget's default DOM element type.
  • Fixed a regression in WDate::addMonths() and addYears(), introduced in Wt 4.0.0. When a day would not exist in the resulting month, this would yield an invalid month. Instead, it will now (as it did in Wt 3) set the date to the last day of that month, e.g. May 31, 2019 + 6 months becomes November 30, 2019.
  • Fixed an issue where mouse signals of a WTreeView would fire multiple times (issue #6260)
  • wthttp WebSocket fixes:
    • WebSocket requests for non-existent sessions (often the result of restarting the server) no longer create a new bogus session.
    • WebSocket messages with continuation frames (as sent by Google Chrome when the messages become very large) could become corrupted, especially when per-message-deflate is used (issue #7039, #7034).
    • WebSocket message size is now properly limited by --max-memory-request-size. Previously, this would only limit the size of individual frames, not the entire message.
    • Fixed a possible use-after-free or double delete issue when an invalid WebSocket message was received.
  • Fixed undefined ackId overflow behavior (which could very rarely cause a session to fail)
  • WContainerWidget::setLayout() now properly clears any existing contents of the container. This would previously cause JavaScript errors (issue #7128).

Release 4.0.5 (December 14, 2018)

Wt 4.0.5 is almost entirely a bugfix release. Here are the key changes:

Minor API breaking changes


One of the things we changed in Wt 4 is the type of roles in the MVC system. They are no longer represented by an enum, but now through a class that's a thin wrapper around an int. We however forgot to update the role's type in a few places, and this release rectifies that. The following methods have been updated:


The UpdatePasswordWidget, part of the authentication subsystem of Wt, would delete itself when done. This was harmless when it was inside of a WDialog, but it's less practical when used elsewhere. We've changed the behavior of UpdatePasswordWidget to emit the updated() and canceled() signals instead.

Dbo: reentrant statement use

For the longest time, the Dbo tutorial has mentioned that “you need to be careful to not have two collections with the same statement busy at the same time”. If you did attempt concurrent use of statements, an exception mentioned that “Reentrant statement use is not yet implemented”. Starting from Wt 4.0.5, you won't see that error anymore. Dbo will now clone the prepared statement as needed.

Flex layout fixes

One of Wt 4's niceties is the fact that the layout managers now rely less on JavaScript, but employ flexbox instead. This did not work perfectly, though, so it was still possible to switch the implementation to the old JavaScript method if things did not work correctly. We fixed many issues in the flex layout implementation, and now the widget gallery works correctly using flexbox (pending an overhaul to make the widget gallery more responsive and more in line with the Wt homepage theme).

Release 4.0.4 (August 22, 2018)

This release brings with it the usual bugfixes, but also some new features:

WCartesianChart improvements

Multiple Y axis support

In previous versions of Wt, it was already possible to have two separate Y axes. This release allows for any amount of Y axes, and extends the interactive functionality to support multiple Y axes.

The following methods have been added:

Small breaking change: note that the virtual method prepareAxes has been modified to take a WPaintDevice* argument. If your code overrides this method, be sure to add this argument to your overridden version.

It's also possible to pan and zoom individual axes by scrolling on or dragging the axis itself, or by touch dragging and pinching.

On-demand loading

We've added on-demand loading functionality to WCartesianChart. Enable on-demand loading when you have a lot of data and/or need the ability to zoom in very far. This will make it so that only the data for the visible X range is loaded, and will improve performance of data series with large amounts data. This becomes especially useful in combination with the ability to set a maximum zoom range, so that you can't zoom all the way out to see all data.

The following methods have been added:


Note that the data must be ordered on X axis value for this feature to work properly.

Path parameters

It's now possible to use variables in WServer::addResource(), e.g. server.addResource(&resource, "/users/${user}").

These parameters are then accessible in the WResource's handleRequest() function through Http::Request::urlParams() and Http::Request::urlParam(const std::string&).

A feature example demonstrating this was added in examples/feature/urlparams.

Idle timeout

Added an <idle-timeout> option to the configuration (wt_config.xml). If set, WApplication::idleTimeout() will be triggered after the configured number of seconds.

This is intended to prevent unauthorized people from using an active session from a device that's been abandoned by the user.


Added the ability to set a JavaScript filter, e.g. to compress uploads client side.

Miscellaneous improvements

  • Added support for transparency in PDFs
  • Rudimentary support for drawing SVGs on HTML canvas with WPainter::drawImage
  • Wt::Dbo::backend::MySQL: Fixed compatibility with MySQL Connector/C 8.0 and MariaDB Connector/C 3.0
  • Added WEnvironment::timeZoneName()
  • Added insertTab, itemAt and currentItem to WTabWidget
  • Disabled TLS v. 1.0 and 1.1 support

Release 4.0.3 (April 12, 2018)

This release fixes compatibility with Boost 1.66, fixes some bugs, and adds some functionality:

WFileUpload: added display widget
Often, native file upload field look out of place in the rest of a web application's design. A common trick is to hide the file upload field, and add another widget that forwards its click signal to the file upload field. We added setDisplayWidget() to make it easy to implement that trick.
WFileDropWidget: added drop indication and global drop
When drop indication is enabled, a WFileDropWidget will be highlighted as soon as a file being dragged enters the page. When global drop is enabled, then a drop anywhere on the page will put the file in the WFileDropWidget.
SqlConnection::executeSqlStateful() allows to execute SQL that should be re-executed upon automatic reconnect. Automatic reconnect is currently supported for the Postgres and MySQL backends.
WTableView: exposed touch events
We made it possible to define custom behaviour upon touch events on WTableView, by adding the touchStarted(), touchMoved(), and touchEnded() signals.

Release 4.0.2 (November 24, 2017)

This is a patch release that fixes a few problems with the build of Wt 4.0.1, and fixes a bug in Wt::Auth.

Release 4.0.1 (November 21, 2017)

This is a smaller release with mostly bugfixes, and some new features:

Added WContainerWidget::addNew() and similar methods

Because writing code like this:

auto text = root()->addWidget(std::make_unique<Wt::WText>("Hello!"));

is a bit verbose, a shorthand was added that creates the widget and adds it to the container in one go:

auto text = root()->addNew<Wt::WText>("Hello!");

addNew forwards its arguments to the constructor, just like std::make_unique. Along those lines, we added WContainerWidget::insertNew() and WTemplate::bindNew().

Added the <max-formdata-size> configuration option
Previously, the maximum size of form data sent by Wt in a single POST request was capped to 5 MiB. In applications with a large amount of forms with a lot of data, that may not be enough, so <max-formdata-size> can be used to adjust this independently. Note that the maximum request size (and by consequence, the form data size) is still capped by <max-request-size>.

Release 4.0.0 (September 19, 2017)

This release has all of the added features of Wt 3.3.8, but comes with many notable changes. In general, Wt 4 employs the more modern C++ style of C++11 and beyond. Support for compilers without sufficient C++11 support is dropped completely. Wt 4 aligns more with the C++ Core Guidelines in a pragmatic way, while keeping the API familiar.

New features since Wt 3.3.8

Microsoft SQL Server backend for Wt::Dbo
We've added Microsoft SQL Server support to Wt::Dbo, making it the sixth backend we support, alongside Sqlite, PostgreSQL, MySQL (and MariaDB), Firebird, and Oracle (not part of the open source Wt because of licensing). With this addition, Wt::Dbo now supports most commonly used relational database management systems. It's based on ODBC and works with Microsoft's ODBC Driver for SQL Server. With unixODBC, Linux and macOS are also supported.
Added support for listening on multiple interfaces and ports to wthttp

With the multivalued --http-listen and --https-listen options, you can now listen on multiple interfaces and ports. For example, if you want to listen on port 8080 on all IPv4 and IPv6 interfaces, you can use:

--http-listen --https-listen [0::0]:8080

--http-listen and --https-listen obsolete the --http-address, --http-port, --https-address, and --https-port options.

Changes in Wt's memory model

Like before, the parent widget (e.g. a WContainerWidget) owns its child widgets. This has not changed. Wt 4 makes ownership transfers more clear by using std::unique_ptr There are no more owning raw pointers in Wt's public API.

By consequence of using unique_ptr, constructors no longer take a parent argument. For convenience, addWidget() now returns a (non-owning) raw pointer. Instead of doing:

// parent is a Wt::WContainerWidget*
Wt::WPushButton *button = new Wt::WPushButton("Click me", parent); // Wt 3: parent owns the button


Wt::WPushButton *button = new Wt::WPushButton("Click me");
parent->addWidget(button); // Wt 3: ownership is transferred to parent through addWidget

You can now do:

// Wt 4 (with C++14's std::make_unique)
Wt::WPushButton *button = parent->addWidget(std::make_unique<Wt::WPushButton>("Click me"));

Wt::cpp14::make_unique can be used instead of std::make_unique if C++14 support is unavailable.

Some classes were changed from the old single ownership model to shared ownership through std::shared_ptr, like models (WAbstractItemModel, WAbstractChartModel, and derivates) and validators.

Wt::Core::observing_ptr was introduced. This pointer will be notified when the object it points to is deleted. observing_ptrs are intended to be used within the scope of a WApplication and are not thread safe. Every WObject (and by consequence, every widget) is an observable, so its lifetime can be observed with an observing_ptr. Their use is entirely optional, but they may be useful when the lifetime of an object is not always clear.

Header files now end in .h

Wt 3 used extensionless headers. This confuses many editors and IDEs. For Wt 4, the .h extension was added, and using the old style headers is deprecated. You can use the Python script migrate/wt4_add_h_to_includes.py to help update your Wt includes.

Enums replaced by enum classes

Many enums were replaced with enum classes, and many have been moved from class scope to namespace scope, e.g.:
enum SelectionMode {
  NoSelection = 0,
  SingleSelection = 1,
  ExtendedSelection = 3
enum class SelectionMode {
  None = 0,
  Single = 1,
  Extended = 3
Some enums were preserved in places were the added verbosity was undesirable, like the Wt::Dbo::RelationType enum.

Replacements for Boost

Many features of Boost that Wt relied on were made obsolete by C++11. Many other Boost features have been replaced with C++11-based alternatives.
Choice between Boost.Asio and standalone Asio
The CMake option WT_ASIO_IMPLEMENTATION allows to choose between boost and standalone Asio.
Removal of Boost usage in Wt headers
If standalone Asio is used, the installed headers of Wt no longer include any Boost headers. The Windows builds of Wt 4 will from now on no longer include Boost, including only the standalone Asio headers instead. This just about halves the size of the installer. If you want to use Boost, you'll have to provide your own. You can find prebuilt Boost binaries for Windows here.
Boost.Date_Time was replaced with Howard Hinnant's std::chrono-based date implementation
The author of the std::chrono standard has created a library for dates and time zones. This library is proposed for inclusion into the C++ standard in the future. For now, Wt includes this date and time zone library (at this moment, this is version 2.2). This is used for all time-related classes, like WDate, WTime, WDateTime, and WLocalDateTime.
Boost.Any replaced by Wt::cpp17::any
WStandardItemModel relied heavily on boost::any. This was replaced with Wt::cpp17::any. You can choose the implementation of any to use with the CMake option WT_CPP17_ANY_IMPLEMENTATION. Valid options are:
  • thelink2012: this is the default implementation, included in Wt
  • experimental for std::experimental::any
  • std for C++17's std::any
Boost.Signals2 replaced with own implementation

Wt did not use many of the features of Boost.Signals2. Since C++11, many more efficient alternatives have been created. Wt 4's implementation, based on this blog post, offers better performance and more understandable stack traces. It's now no longer necessary to use std::bind with lambda functions, e.g.:

button->clicked().connect(std::bind([]{ std::cout << "Clicked!" << std::endl; })); // Wt 3

can be changed to:

button->clicked().connect([]{ std::cout << "Clicked!" << std::endl; }); // Wt 4

Boost.Signals2, together with boost::bind, allowed you to automatically disconnect slots when one of their bound arguments was deleted, if the argument was a derived class of boost::signals2::trackable. In Wt 4, this is no longer the case. Instead, you can provide a target WObject as the first argument to the connect function, and Wt will disconnect the slot when the target WObject is deleted.

WApplication::bind has been removed, and instead observable::bindSafe was introduced. bindSafe will guard the observable, returning a function object that doesn't do anything if the observable has been deleted.

Other Boost libraries obsoleted by C++11
Boost.Thread, Boost.Regex and Boost.Random were mostly replaced by their STL counterparts. Only Boost.Thread is used internally in Wt 4 because Wt uses some mutex functionality that's not part of C++11.

Other changes:

  • ItemDataRole is now a class instead of an enum.
  • Wt 4 assumes that std::string is UTF-8 encoded by default, so WString(std::string) will assume that the argument is UTF-8 encoded. Overloads for new C++11 string types (std::u16string, std::u32string) have been added.
  • Intervals and other durations previously indicated by ints have been replaced by std::chrono::durations, e.g. in WIOService::schedule() or Wt::Http::Client::setTimeout().
  • WBoxLayout is now implemented with flexbox instead of JavaScript by default. Wt will fallback to the old JavaScript implementation when functionality unavailable in the flexbox implementation is used, use WBoxLayout::setPreferredImplementation to set a preferred implementation.
  • setObjectName() no longer affects the id of a widget. Instead, it is placed into an extra attribute called data-object-name. selenium/wtLocators.js has been updated to reflect this change.

Removal of deprecated functionality

  • Everything that was marked as deprecated in Wt 3.3.7 has been removed, including Wt::Ext.
  • WScrollArea was removed, use CSS or WContainerWidget::setOverflow() instead.

Release 3.3.8 (August 16, 2017)

This release consists of bug fixes and some new features:

OpenID Connect support
As we've previously announced on our blog, Wt now supports OpenID Connect. All you need to do to use any OpenID Connect based service is configure a Wt::Auth::OidcService. You can also make your own OpenID Connect identity provider. Check out the accompanying OpenID Connect feature example.
On Windows: font support based on DirectWrite

Wt 3.3.7 already introduced the Direct2D backend for WRasterImage. Wt 3.3.8 further expands on this by adding DirectWrite-based font support. This means that Wt 3.3.8 will be able to select the appropriate fonts for every glyph, without requiring Pango. Pango was always difficult to distribute on Windows, so we never included Pango in the binary distribution, relying on very basic font support instead, replacing unknown characters by question marks. Now, you can expect much better Unicode support with DirectWrite on Windows.

This means that the binary release of Wt on Windows is now built with Direct2D and DirectWrite.

Wt::Dbo: added sql_value_traits for Wt::Json::Object and Wt::Json::Array.

Quite often, the need arises to store some unindexed data with arbitrary structure in a database. A common solution is to store JSON as a string. To facilitate this, we've included implementations of sql_value_traits for Wt::Json::Object and Wt::Json::Array in Wt/Dbo/WtSqlTraits. This allows you to store Wt::Json Objects and Arrays just like you any other field.

Additionally, we've made the Wt::Json API a bit more friendly, by adding support for initializer lists (when using C++11), and implicit constructors for Wt::Json::Value from Wt::Json::Object and Wt::Json::Array.

Added <allowed-origins> configuration option for CORS
Wt used to allow almost any origin, to allow Wt applications to be embedded in any page using WidgetSet mode. Although Wt encodes session IDs in URLs rather than cookies by default, this could still pose a security risk in some cases. In Wt 3.3.8, CORS support has been updated: Wt now only allows cross-origin resource sharing for WidgetSet entry points, and trusts no origin by default. You can specify the allowed origins using the <allowed-origins> tag in the configuration file. Using <allowed-origins>*</allowed-origins> restores the old behaviour.
Other small improvements:
  • Any boost::asio::io_service can now be used with Wt::Http::Client, instead of just Wt::WIOService.
  • Added support for PATCH requests in WResource and Wt::Http::Client, next to GET, POST, PUT, and DELETE.
  • wthttp connector: added support for forward secrecy with the --ssl-prefer-server-ciphers option.
  • Added the num-session-threads configuration parameter, to set the amount of threads per session when using dedicated process mode. By default, the main process and the session threads use the same amount of threads.
  • The te-benchmark example was added, implementing the TechEmpower framework benchmarks. This example also demonstrates how Wt can be used to write RESTful services. Improved, less verbose, support for RESTful services is planned in a future release.
  • Added Wt::Dbo::FixedSqlConnectionPool::setTimeout(), to set a timeout for obtaining a connection.
  • Added Wt::Dbo::backend::Postgres::setTimeout(), to set a timeout for queries.
  • Added libunwind support for printing stacktraces. Enable this with the ENABLE_UNWIND CMake option.

Release 3.3.7 (March 31, 2017)

This release fixes many bugs, but also introduces some new features:

The WFileDropWidget is a new widget that allows you to upload a file or multiple files by dragging them onto an area.
Scroll visibility
Some applications require you to know whether a widget is currently visible within the viewport, or whether it is scrolled out of view, e.g. to load more content as you scroll down the page. You can now enable scroll visibility detection with WWidget::setScrollVisibilityEnabled(bool), and react to changes in visibility with WWidget::scrollVisibilityChanged(). A new scrollvisibility feature example has been added to demonstrate this infinite scrolling application.
Touch events
Although Wt already supported touch interactions in the charting library, touch events were previously not exposed by Wt. Now, we've added WTouchEvent, and the touchStarted, touchEnded, and touchMoved events have been added to WInteractWidget. Also, draggable widgets can now also be dragged after a long press, and you can select a range using a double touch in WTableView and WTreeView.
Combined session tracking mode

The default session tracking method for Wt is URL rewriting, using JavaScript to hide the session id from the address bar. Alternatively, cookies can be used with the Auto option, falling back to URL rewriting when cookies are not available. However, the cookie-based method did not allow for multiple sessions within the same browser.

In order to make the URL rewriting method with requirement 6.5.10 of the PCI Data Security Standard, while not sacrificing the ability to have multiple sessions, a new Combined session tracking strategy has been added. Wt already makes it difficult to steal a session when the session id is discovered, but resources are not as protected. The Combined session tracking strategy uses URL rewriting in combination with a cookie that is shared between sessions as an extra measure against session hijacking. This is the most secure strategy, but it will deny access if cookie support is not available.

Wraparound for WSpinBox and WTimeEdit
WSpinBox will now wrap around from its maximum to its minimum if you enable wraparound. WTimeEdit will take advantage of this feature by default.
On Windows: Direct2D implementation of WRasterImage
We've added another implementation for WRasterImage on Windows: Direct2D. When building Wt, this implementation will be enabled by default. This allows to remove the dependency on GraphicsMagick or Skia on Windows, simplifying the build process.
Some minor extra features:
  • It's now possible to retrieve a vector of all request headers with Wt::Http::Request::headers() in handleRequest when implementing a WResource. It is still recommended, and more efficient, to use headerValue, but retrieving a vector of all headers could be useful for debugging purposes.
  • In an effort to reduce the amount of JavaScript generated by the charting API, the WPainter::drawStencilAlongPath() method was added to WPainter.
  • Previously, WDialogs were movable by default. It's now possible to disable this with WDialog::setMovable().

Release 3.3.6 (July 13, 2016)

This release has a focus on bug fixes and some new features:

Support for WebSocket compression in wthttp
WebSocket traffic is now compressed, if possible.
Time entry improvements
WTimeEdit now supports AM/PM in its format, WTimeValidator now allows to select a minimum and maximum time and supports multiple formats, WTimePicker can now work up to millisecond precision, and is now rendered with spinboxes.
Skia version updated
The Skia backend for WRasterImage is now compatible with more recent versions of Skia. If you need to support an older version of Skia, use -DWT_SKIA_OLD=ON. The Skia version of the Windows builds has been updated from 394c7bb to 834d9e1.
  • It's now possible to mark foreign keys as literal with a “>” prefix, so Wt::Dbo can better map to an existing schema. Note that for consistency, this also means that the schema generated for ManyToMany relationships has been changed to include the id column names if a joinId has been specified. If you specify a joinId for ManyToMany relationships, you'll have to change it to include a “>” before it in order to keep the same database schema.
  • The size argument of belongsTo() has been removed, since it served no actual purpose.
Scroll position
It's now possible to retrieve the scroll position of a WContainerWidget with scrollTop() and scrollLeft().
Invalidation of stateless slots
WObject::isNotStateless() has been added, so functions called from functions that are marked as stateless can unmark it as stateless, reverting to plain server-side dynamic UI updates.
The Dbo UserDatabase implementation now compares e-mail addresses case insensitively. The AuthService can be passed in the constructor, so the UserDatabase knows whether the IdentityPolicy is EmailAddressIdentity.
Charting library
There have been many bug fixes and improvements to the charting library and the interactive features introduced in Wt 3.3.5:

Release 3.3.5 (Dec 31, 2015)

This release has a focus on bug fixes but also one or two new features:

WCartesianChart has several new features that allow interaction with the chart without server roundtrips. These features include zoom, pan, crosshair and follow curve functionality. This is only available if the chart is drawn on an HTML canvas. This is the default rendering method on modern browsers. When enabled, the crosshair will follow mouse movement, and show in the top right corner the coordinate (according to X axis and the first Y axis) corresponding to this position.
WAxisSliderWidget lets you easily focus on a particular range by selecting an XAxis. It will create a sliding widget where you can change the size of the focused region by dragging the blue handles, and change the position by dragging the selected area. When using touch, the size of this area can also be changed using a pinch movement.
WPainter, WJavascriptHandle, WCanvasPaintDevice
The above functionality was implemented by making client-side interaction possible for a scene rendered on WCanvasPaintDevice. For this purpose, for several primitives used to draw on a canvas, we provide a JavaScript handle and complementary API to manipulate these objects in JavaScript code. In this way you can keep the bulk of the painting code in C++, and allow manipulation from within JavaScript. Such JavaScript handlers have been made available for WTransform, WPen, WBrush, WPointF, WRectF and WPainterPath.
WAnchor target (such as this window, or new window) moved to WLink
As WLink is used in several places (including for example inside item data models), the target can now be specified in more places in the same consistent way. However, since until now a WAnchor was the owner of the TargetType, this may break existing code which calls WAnchor::setTarget() before WAnchor::setLink(), as the latter overrides the target.
A new TargetDownload target was added for links.
Until now it was recommended to use TargetNewWindow as otherwise this would interfere with the rendering of the current page (since browsers are unaware of the content-type and content-disposition of the target link until after it unloaded the current page. The new TargetDownload option is implemented using the new HTML5 download attribute or, if not supported, by targeting a hidden iFrame contained in the page.
The included SQLite version was updated
The SQLite version bundled with Wt::Dbo has been updated to version The changelog can be found here
Support for seconds editing in WTimePicker
WTimePicker was missing the seconds, we've also added the setSecondStep() method.
Before it was only possible to set the partial state of the WCheckbox when creating the Widget. We've added a method WCheckBox::setPartialStateSelectable(bool) which will allow the user to select indeterminate state. This is false by default;
New client side connection monitor
The WApplication::setConnectionMonitor() method will let the user register a Javascript object that will be notified on connection changes (connection, disconnection, websockets enabled/disabled..) The monitor will trigger the onChange method of the provided Javascript object
Support for custom HTML tags for a widgets
We've added WWebWidget::setHtmlTagName() that will change the current html tag instead of using the one chosen by Wt by default. This allows the user to create widgets that are not provided by Wt, such as for example semantic tags.
Wt::Dbo: allow to forward declare related classes
It is now possible to forward declare all classes that are being referenced in a belongsTo(), hasOne() or hasMany() relation, helping to reduce the compile time pain of Wt::Dbo.

Release 3.3.4 (Mar 25, 2015)

This release has a focus on bug fixes but also one or two new features, of which the following are the most notable:

Support for dedicated session processes with wthttp connector.
Until now, only the FastCGI connector allowed the use of dedicated processes for individual sessions, by spawning a new process for each new session. This functionality has also been added to the wthttp connector. In this implementation, the manager process will act as a reverse proxy to the dedicated session processes. This has as major benefit that there is no longer a choice between dedicated session processes on the one hand (supported by FastCGI) and support for WebSockets on the other hand (supported by the built-in httpd). In fact, there remains little reason to prefer FastCGI over the built-in httpd: in those situations where you want a proper http server as a front-end, you can still use HAproxy or NGINX (or Apache, if you must) as a reverse proxy to wthttp.
This new proxy model simply forwards the structure of the source model, without any transformation, and can be used for implementing proxy models that reimplement data(), but retain all other characteristics of the source model.
Until now, you were responsible for configuring the padding around the chart area to accommodate for axis labels, titles, and legend. While this is still the default behaviour, we added an option to let the chart derive the required padding (using approximate font-metrics available server-side).
Whereas previously a chart axis was a "value class", it is now a proper polymorphic class, and you can provide your own implementation. In this way you can customize things like for example label strings.
Several new features in the 3D charts library.

Release 3.3.3 (May 27, 2014)

This release has a focus on bug fixes but also one or two new features:

Improved Meta header support.
Because WApplication meta header API was restricted to only work in certain circumstances, we have now added the ability to define meta headers (with the option to apply them to specific user agents) also in the configuration file.
This function is an alternative to setToolTip(), useful when a tooltip text is not trivial to fetch or create. Using this function, the tool tip (HTML) text can now be loaded on-demand instead of needing to be preset on (each) widget. This also works for tooltips set from a WAbstractItemModel using the new ItemHasDeferredTooltip item flag.
Support for input masks was added, which guides the user to enter data in the correct format.

Release 3.3.2 (March 12, 2014)

This release has a focus on bug fixes and a few larger new developments.

A) New classes:

3D Charts (Chart::WCartesian3DChart, ...)
A 3D charting library was added, based on WGLWidget, and integrated with the existing 2D charting framework.
This is a utility which serializes Dbo objects (including relations) to JSon, leveraging the same persist() function used for serialization to the database.

B) Main improvements:

Support for bootstrap version 3 was added, so now you have the choice between bootstrap version 2 or 3. Needless to say, you should probably target version 3 for new development work if you can live with its restricted browser support.
Next to the existing client-side WebGL-based implementation, a server-side OpenGL-based implementation was added for fallback scenarios where WebGL is not available, or when scene complexity is so big that a server-side solution is simply better performing because of lower bandwidth needed.
Next to the GraphicsMagick-based implementation, a skia-based implementation has been added (which provides much higher performance most notably on Windows platforms).
Until now, Wt defaults to the C++ global locale for conversion between a string literal (std::string, const char *) and WString. In practice, UTF-8 is an (increasingly) better choice since UTF-8 is a pragmatic encoding covering the entire Unicode range, and the encoding used by the library throughout. We've now added a setDefaultEncoding() function which can be used to configure the default encoding as UTF-8.
wthttp HTTP/WebSockets front-end server
We've given the http front-end a much needed overhaul, making it deal better with long-lived connections typical for WebSockets applications, and fix some nasty issues at the same time. We also took the opportunity to optimize its performance by reducing the number of system calls for writing request responses, and by avoiding memory allocations during request parsing.

C) Non-backwards compatible changes

WDatePicker, WDateEdit
The date pickers will now default to interpreting a single click as a date selection and also closing the calendar.

Release 3.3.1 (October, 16 2013)

This release has a focus on bug fixes and other cleanups after the big changes that went into 3.3.0.

A) New classes:

So far, the library only provided date/time classes that dealt with UTC time (or that at least is the intended use). In this release we have added functionality to also deal with date's in a specific time zone, which includes this new type as well as improvements in WDateTime to convert to local date time, and time zone information in WEnvironment and WLocale.

B) Main improvements:

The combo box now interprets LevelRole data to display headers (using HTML <optgroup< elements). Another improvement is that now the combobox saves its single selection while the model is updated.
Modal dialogs can now be created and destroyed in any order without confusing the 'silk screen'. We now also consistently interpret an enter press in the dialog to invoke the default button added to the dialog footer (if there is one).
Several improvements include the ability to indicate what buttons are the default and escape buttons with setDefaultButton() or button->setDefault() and setEscapeButton(), and the (long overdue) implementation of icons!
We've added support for TinyMCE 4.
For boost versions 1.52 or later, we now support the Boost.Signals2 library for the signals implementation.
Render library
We've added a CSS style sheet parser which will parse and apply style rules in <style> blocks (or loaded through the API), and expanded CSS support to improve table rendering (including border-collapse border model and repeated table headers), relative/absolute positioning, and page-break-before/after support.
A setIdentity() method was added to modify an existing identity (e.g. username) and updateAuthToken() was added to update an existing token (e.g. keeping the expiration time but changing the hash).
Added a reset() function which resets previous bound arguments.
The model now implements toRawIndex() and fromRawIndex() methods to allow selection to persist across layout changes (e.g. resorting).
Wt::Json (JSON library)
We've added serialization functions to complement the parsing API.
Wt::Mail (SMTP library)
We've added attachment support, and optional indication of the local sender date.

C) Non-backwards compatible changes

WDate, WDateTime WTime
We've deprecated the exceptions (Invalid[Date][Time]Exception) that were thrown by these classes when one attempted to compute or use an 'invalid' value. These exceptions are no longer thrown. Instead, we now documented what value (usually 'null') is returned when one attempts to do operations on such a date/time class, which makes the behaviour more consistent with how Qt's equivalent classes behave.
The buttons() method has been renamed to standardButtons(), and buttons() now return the actual list of added buttons.

Release 3.3.0 (April, 8 2013)

This release focuses on a reorganization of Wt's theme infrastructure, with the objective of supporting Twitter's Bootstrap CSS framework as a new theme. At the same time we've added a number of widgets for which Twitter Bootstrap provides styling.

It is our intention to support the Bootstrap theme (or more specifically, the Bootstrap class names) alongside the themes we already supported (which are based on our own class names). Ignoring what Bootstrap brings, you should be able to upgrade to this release without too much trouble, although you may need to adapt some CSS stylesheets as we did reorganize a number of things which were required for Bootstrap and were a good idea for our own CSS stylesheets too.

A) New classes:

WTheme, WCssTheme, WBootstrapTheme,
Theme support classes for Wt. The role of a theme is to:
  • Load the CSS stylesheets for a new session
  • Annotate newly created widgets with appropriate style classes
Functionally almost the same as a WDatePicker, this class specializes WLineEdit and is thus a WFormWidget, making it much easier to use in WTemplateFormView.
This class supports localization for number formatting and extends the simple localization support we had in the previous versions of Wt (which as only effect had the selection of a different language for the resource bundles). It's main added value of native C++ support for localization is that it also affects client-side handling and parsing of number values, i.e. in WIntValidator and WDoubleValidator.
A navigation bar styles a menu as a typical top-level bar (currently only styled in the Bootstrap Theme).
A base class to simplify the creation of popup widgets that typically assist in editing or provide circumstantial information for another widget.
A split button, which combines a button and a popup menu (currently only styled in the Bootstrap Theme).
A button tool bar (currently only styled in the Bootstrap Theme)
A MariaDB/MySQL backend for Wt::Dbo. This is based on the work from Paul Harrisson who maintained this backend so far outside the Wt distribution. The backend has been designed for MariaDB, but should work fine for MySQL as well.

B) Main improvements:

Added API support for additional SMTP headers.
WDatePicker, WSuggestionPopup
The setGlobalPopup() functionality has been deprecated and does no longer have any effect, since a new improved algorithm is being used to anchor the popup to the DOM which no longer requires this workaround.
Addition of a footer() method that returns a container for dialog footer elements, typically buttons.
Addition of a validator() function that returns the validator for a field set using setValidator(),
Support for binary transfers which avoids serialization and deserialization of floats to text.
A push button can now act as a toggle button, using setCheckable() and related API (currently only styled in the Bootstrap Theme) and can be linked to a popup menu using setMenu().
When switching between current widgets, the stacked widget will now record and restore the current scroll position, providing a much improved user experience when using the stacked widget for the 'main' contents of an application.
Full support was added for storing data of all roles, lifting the requirement to use another model such as WStandardItemModel for simple MVC widgets like WComboBox or WSuggestionPopup simply to be able to store UserRole data.
Added a new standard function (Functions::block) which allows the definition and use of a macro block inside a placeholder, which is in particular useful for forms which have repetitive formatting for each field.
Several API improvements: A new setFormWidget() allows the definition of the form widget for editing a field which is a more useful alternative compared to reimplement createFormWidget(). It also allows the optional definition of functions to update the view/model values, which avoids the need for specializing updateViewField() and updateModelField() these latter two functions have been deprecated in favour of two new functions updateViewValue() and updateModelValue() which only update the value but not other aspects such as visibility, validation state, or messages.
Built-in httpd improvements
A redundant copy operation of the response generated and sent by Wt has been removed, using scatter-gather I/O implemented by boost::asio instead.

C) Non-backwards compatible changes

While in previous version of Wt, this class was only a data class that held the information related to an item, in 3.3.0 we modified this so that this class represents the widget itself. If you were redefining protected methods to customize the widget (i.e. createItemWidget() and updateItemWidget()), then this will no longer work as expected. The new system should be easier to customize (since you can simply specialize WMenuItem itself). In addition, we've simplified the rendering of a menu item so that a redundant layer of spans (or div's) has been removed. It makes the menu more consistent with the way CSS designers expect a menu to rendered, and this was done (you can guess the theme of this release by now ?) to be compatible with bootstrap's CSS styles.
This now returns a WLocale object instead of the string designation of the locale (which you can query by calling name()) on the locale object.
The markup for this class has changed, and thus customized CSS will need to be updated.
The popup menu item class has been merged with WMenuItem (and WPopupMenu is now a specialized WMenu). This should not have noticeable API changes, except for the changes in markup and CSS documented above.
WTreeNode, WTreeTable WTreeView
The markup for tree rendering has been changed (to using nested unordered list instead of nested tables), and thus customized CSS will need to be updated. The only API consequence is that WTreeNode::labelArea() is no longer returning a WTableCell but instead a WContainerWidget.
WTreeView, WTableView
Event handling (clicked(), doubleClicked(), ... ) has been generalized: events that are not generated on an item (but for example in empty space below the items) will now also generate these events, but then with an invalid model index. You may thus need to adapt current code to check whether the model index that is returned is valid.

Release 3.2.3 (November, 1 2012)

This release contains mostly bug fixes and one new feature: a payment processing API.

A) New namespaces:

Wt::Payment (payment handling)
This namespace contains services and back-end classes for dealing with online payment brokers. At the moment there is support for PayPal's Express Checkout service.

B) Main improvements:

Layout improvements.

If you had massive trouble migrating to 3.2.2 because of the layout rewrite, then you'll appreciate the efforts we've made to make the layout algorithms in 3.2.3 much more robust and consistent.

Dbo::QueryModel: added a mechanism for stable row data.

A common nuisance when working with the QueryModel (which retrieves data from the database as needed), is that concurrent database modifications such as insertions of new data, may interfere with the model's mapping of rows to objects (this is in fact a common problem with most ORM's indeed). This mapping may be important, especially when you want to process the user's selection of one or more rows selected by the user, in e.g. a table view. We've added a mechanism to assure that one can request the model for data at a given row, which is guaranteed to be the same row that has been previously retrieved, using the stableResultRow() method. It works by default for simple queries (returning data from one table), but can be easily customized for more complex queries.

Render library: improved support for %-based block sizes and table rendering

Support was added for %-based sizes for block widths and table cell widths. In addition, table rendering in Wt::Render has been improved to support repeating headers (<thead> sections) for multi-page tables, and explicit page breaks (using the css page-break-after/before properties).

C) Non-backwards compatible changes


We've changed the implementation of the storage ISO8601AsText format for time stamps (datetime). In the new, corrected, implementation, we generate dates using 'T' as the separator between date and time (as mandated by ISO8601), while the old behaviour used a space (' ') instead as the separator. Sqlite3 supports either format equally. This may however break some applications which use queries for an exact date (or a date comparison), as the results may be affected.

The old behaviour is still available as PseudoISO8601AsText, which can be configured using connection.setDateTimeStorage(Wt::Dbo::SqlDateTime, Wt::Dbo::backend::Sqlite3::PseudoISO8601AsText)

Release 3.2.2 (July, 23 2012)

This release contains mostly bug and feature improvements, but also a rewrite of the layout managers in Wt (WBoxLayout and WGridLayout), and this comes with some changes in (in most cases previously undefined) behaviour.

A) New classes:

Class containing information on a client-side certificate that may have been configured for a SSL connection, and which can be used for authentication (accessible from WEnvironment).
A weak variant of Wt::Dbo::ptr which is used to implement One-to-One relations (see also Wt::Dbo::hasOne() ).

B) Main improvements:

Rewrite of WBoxLayout, WGridLayout

The layout managers have been reimplemented, to address various issues with the old implementation, including API (in particular the wonky side-effects of AlignTop | AlignJustify) inconsistencies and bugs.

The new implementation no longer uses tables when JavaScript is available, but instead using JavaScript-based layout with absolute positioning. The table-based implementation is still kept for plain HTML sessions (and progressive bootstrap). The code now uses exactly the same layout logic for both horizontal and vertical layout (but giving precedence to horizontal layout) and should be much more consistent (and perhaps also more performant). However, because of the many complexities and problems with the old code (inconsistent behaviour), you may see issues while upgrading. Please see the "Non-backwards compatible changes" below for hints on how to deal with this.


A drag & drop mime-type can now be specified on a per-item basis using a new ItemDataRole, and the mime-type for the entire selection is computed from these individual mime-types.

A new method setMouseOverDelay() allows to specify a delay for generating the mouseWentOver() event.
A new method deleteUser() was added, which deletes a user and all related authentication information.
A new method setAxisPadding() was added, which configures the amount of adding between the chart area and the axes.
A new method setCustomMarker() was added which allows the use of a user-defined path for the markers. A new role MarkserScaleFactorRole was added which allows overriding the marker size based on item model data.

C) Non-backwards compatible changes

WBoxLayout, WGridLayout
While migrating old code to this version, here are some tips:
  1. Alignment flags

    Previously, specifying an alignment for a widget in a layout, or for the layout when set to a container, had a double meaning. Not only would it implement the given alignment but also revert to passively letting HTML layout decide the layout of the contents, and adjust the parent (layout respectively container) accordingly. This had all kinds of side effects such as not propagating the size of layout-size-aware widgets and quirks in the vertical alignment.

    WContainerWidget::setLayout(layout, alignment) has been deprecated and will be removed from a future release. This call was almost always used to let the parent container resize to fit the size of the contained children, instead of fitting children in the parent container. This behaviour is now automatically deduced based on an (empty) size of the parent container. In case this heuristic does not work, then setting a non-0 maximum size on the container using setMaximumSize() will act as a trigger, with the added benefit that the parent will only be allowed to resize up to a specified maximum size.

    An alignment specified in W(Box/Grid)Layout::addWidget(widget, stretch, alignment) now purely affects the alignment but has no other side effects. The preferred and minimum sizes of a child widget or layout is now always taken into account.

  2. Child item sizes

    The layout algorithm is now implemented entirely in JavaScript, and is more gentle when dealing with a combination of cells (or columns/rows) that have a stretch factor and others that don't. Previously, a minimum (or fixed) size would be used to layout items that do not have a stretch factor. This had for example as a consequence that a WText would be narrowed down to its minimum width by using word wrapping throughout. Now, the preferred size is used for a child item, and shrinking to a minimum size only if necessary.

  3. Progressive bootstrap

    A layout in the first page of an application rendered using progressive bootstrap will no longer fully upgrade to a full JavaScript version, but will result in a hybrid (between table-based and JavaScript-based). If it doesn't work out as you'd expect, then you should reconsider the use of progressive bootstrap, or the use of a layout manager in your first page.

Release 3.2.1 (March 16, 2012)

This release contains mostly bug and feature improvements.

A) New classes:

A model class for forms. These models are used in Wt::Auth as the basis for RegistrationModel and AuthModel, and allow a more straight-forward customization of the underlying behavior of these forms.
A proxy model class which allows to share a source model read-only between multiple sessions.
A WTemplate-based standard view implementation that works in conjunction with WFormModel.
A model that implements authentication logic.
An OAuth-2.0 based authentication service implementation for Facebook.
This namespace contains a number of utility functions that we found useful in projects using Wt. They relate mostly to lower-level encoding and decoding functions: base64-, hex-, html-, and url-encoding/decoding.

B) Main improvements:

A new method, WApplication::bind(), is useful in combination with WServer::post() to avoid posting to a method of a deleted object, leveraging the same life-time tracking as with signal connections.
Render library
A large number of performance improvements, especially for table layout and rendering.
DateScale and DateTimeScale axes have improved auto-configuration of limits and timesteps, now taking into account the resolution.
We've modified the default transaction outcome: a transaction will now automatically commit(), unless the transaction is being destroyed (goes out of scope) because an exception is being thrown, in which case the transaction will rollback(). Previously, an uncommitted transaction would always rollback() on destruction.
Added a session() method, returning the session with which the session has been associated.
Shipped SHA-1 implementation.
We now ship a SHA-1 implementation with Wt and this thus relaxes the need for OpenSSL to implement WebSockets and Auth::SHA1HashFunction.

C) Non-backwards compatible changes

Due to backwards incompatibility of IE9, we now require the latest version of TinyMCE (3.5b1 or later).
A number of API methods that configure and access the configuration were moved to the new Auth::AuthModel class which can be accessed from the widget using model().
The API was simplified to be less unorthodox: validate() now returns a Result that contains all the information for it.
We've changed the signature of the parseUrl() utility function to parse the URL into a URL structure instead of a collection of string parameters.

Release 3.2.0 (November 29, 2011)

This release contains a number of new modules, as well as the usual batch of bug fixes and small feature improvements.

In this release we also change the WValidator API in a way that it is likely to break existing applications.

A) New namespaces:

Wt::Json (JSON handling)
This namespace contains classes (Object, Value, Array) which map the JSON types in C++. It also contains a parser to deserialize JSON. A writer to serialize to JSON hasn't been added yet.
Wt::Mail (SMTP protocol)
This namespace contains a Client to send mail messages. It is currently offering only limited functionality w.r.t. SMTP protocol handling, but contains enough functionality to send standards compliant plain-text/HTML mails, with full support for unicode.
Wt::Auth (Authentication)
This namespace contains model and view classes for authentication. It implements password authentication using best practices, email verification, remember-me tokens, and provisions support for federated login with an implementation of OAuth 2.0 for authentication using third party identity providers.
We expect that the API may still evolve, especially with respect to OAuth 2.0 (which is a draft protocol), and its use for OpenID Connect, which is the main use case for OAuth within the authentication module.

B) New classes:

We have cleaned up the use of exceptions within Wt. We have converted numerous cases where an exception used to be thrown to error logging, if the exception was thrown to indicate an API problem. When the API problem is not resulting in a corrupt state, we now log the error instead of terminating the session. All other cases now use an exception that implements WException. This does not affect situations where a std::exception was advertised in the API.
Previously, boost::asio was used only in the built-in httpd as a portable asynchronous I/O reactor implementation. We have now moved this into the Wt library itself, where it is now used instead of a dedicated thread pool for dispatching requests (and other server events), and where it is also used for asynchronous I/O by e.g. the Http::Client.
The WIOService specializes a boost::asio::service, and integrates the thread pool that runs the service.
This is a utility class that we have used since long in Wt. It is a more efficient replacement for std::stringstream, with mostly a compatible API (at least for our purposes). For our purposes it is typically a factor of two or more faster.
Http::Client, Http::Message
We have added an implementation of a Http(s) client. The client is intended for consuming web services in Wt, and handles GET or POST requests. It is not suitable (yet) for large responses, since it buffers the entire response internally.
The client uses asynchronous I/O, using the WIOService that is found in the current WServer instance.
Lukasz Matuszewski contributed a Firebird backend implementation, thanks !

C) Main improvements:

Added a setHeaderWordWrap() method which configures header text word wrapping, and changed setHeaderAlignment() so that it now allows to change both the horizontal and vertical alignment. This replaces the previously interwoven API for both features using the multiLine parameter in setHeaderHeight(), which has been deprecated. The rendering of the header items has been reimplemented, simplified, and cleaned up in the process, avoiding rendering problems on IE browsers.
Two new methods, deferRendering() and resumeRendering() can be used to defer the rendering phase in response to the current event-loop request. This is useful for situations where you are waiting for an asynchronous operation to complete, but want to handle this synchronously in the user-interface (i.e. blocking the interface until the operation completes). While this is not a good idea in general, it may be useful if you can guarantee that the event will arrive within an acceptable time (e.g. 1 second). This effectively stalls the response to the current request, but avoids blocking threads in the process.
Added setClosable(), which adds a close icon into the title bar.
We have cleaned up the use of exceptions within Wt. We have converted numerous cases where an exception used to be thrown to error logging, if the exception was thrown to indicate an API problem. When the API problem is not resulting in a corrupt state, we now log the error instead of terminating the session. All other cases now use an exception that implements WException. This does not affect situations where a std::exception was advertised in the API.
We have reorganized the logging within Wt. Internally, a number of macros are now used for logging, with as default implementation our own (simple) logger, but which can be redefined to use instead another logging framework of your choice, as some have rightfully requested.
But we've also improved our logger so that it now can be configured to filter only certain information, based on type and scope. This is mostly useful for debugging and development of Wt itself, since it allows us to switch on debugging output, in a fine-grained way, in a debug build.
Finally, a new global function has been added (Wt::log()) which selects an appropriate logger for logging and is more convenient than WApplication::log() which required an application instance.
Arguments to bound functions are now parsed and passed to the resolveString() methods.
Two new constructs have been added: conditions and functions. Conditions allow certain parts of a template to be skipped or included based on a bound condition. Functions are useful to automatically resolve certain variables, two built-in functions are implemented: one to resolve strings in a message resource bundle ("tr"), and another to resolve the id of a bound widget ("id").
We've added front() methods that return the first element.
Built-in httpd connector
We have expanded the WebSockets implementation to cover newer versions of the WebSockets protocol (draft): next to 00, we now also support 07, 08 and 13 protocols (with draft-17 semantics).
On UNIX-like platforms, and using the built-in httpd connector, SIGHUP is caught in the WServer::waitForShutdown() utility function, and the configuration file (wt_config.xml) is reread.
Several security improvements
DoS mitigation
We have added two measures to prevent DoS attacks that try to exhaust the server by spawning sessions. This is in particular a risk when deploying using the progressive bootstrap method, since then a plain HTML session can be spawned with a single request.
  • Plain sessions may be limited to constitute only a fraction of the total number of sessions. This is configured using the <plain-ajax-sessions-ratio-limit> configuration option.
  • Ajax sessions need to confirm their "intelligence" by solving a puzzle which requires them to properly parse the (ever-changing) JavaScript and HTML.
Compromised session ID risk reduction
A compromised session ID no longer can be used to hijack that session.
  • A full page refresh (using the session ID to rerender the current application state) is no longer allowed unless both client IP address and user-agent are unchanged. To still enable page refresh in this situation, you may configure the use of a cookie which can be used to confirm the original browser (although that cookie will not be used for session tracking), using the <session-id-cookie> setting.
  • The session ID cannot be used to POST events to an Ajax session, since these require proof of other ever-changing context specific information, notably a pageId and ackId.

D) Non-backwards compatible changes

Build options
The HTTP_WITH_SSL option has been removed, and is now replaced by WT_WITH_SSL -- OpenSSL is now a dependency of Wt inherited by the httpd.
We broke the validate() method, to return a new WValidator::Result instead of WValidator::State. The main improvement is that the validation may also return a text which contains information on why validation failed. This makes the API consistent with the client-side API, and obviously much more useful. It will break existing application that call validate() or have reimplemented validate() in a custom validation class.
This class has moved to a pseudo-connector library (libwttest). This was needed to be able to use asynchronous I/O (such as Http::Client) in test cases, which rely on a WIOService furnished by a WServer instance.

Release 3.1.11 (September 23, 2011)

This release contains many bug fixes and a few new features.

A) New classes:

This class unifies the different link types used in Wt, in a single value class. Depending on the context, a link may refer to a URL, a resource, or an internal path. We've updated the API throughout to replace the function overloads for these different cases with a single usage of WLink, simplifying the API (but don't worry, we left the old methods, albeit deprecated).
A media player has been added which provides a unified framework for playing audio and video, and which deals with cross-browser issues (choosing a suitable implementation per browser). We've also renamed WHTML5Audio, WHTML5Video, and WHTML5Media to WAudio, WVideo and WAbstractMedia respectively (since well, everything will eventually be HTML5, no ?).

B) Main improvements:

WResource, Http::ResponseContinuation
Currently, you can already stream the output of a big resource in little chunks, using a continuation to resume sending the next part. We've now added API methods (WResourceContinuation::waitForMoreData() and WResource::haveMoreData()) to allow a resource to suspend its response because it is currently lacking more data, to continue later when new data is available (and without tying up a thread).
Added an option setResizable() which puts a resize handle in the bottom right corner.
WPopupMenu, WPopupMenuItem
Added a triggered() signal, and an option to automatically cancel the popup menu when the mouse leaves the menu (after a delay). We've also added the possibility to link a popup menu item with a WLink, and the option to make the item which has a submenu item also itself selectable.
The load() method has an additional, optional parameter, to force rereading the copy from the database.
Added a count() method which uses a query to determine whether the collection contains an element.
Added dialogExecuted() and popupExecuted() methods which allow to interact with a reentrant eventloop from a test plan.

C) Non-backwards compatible changes

The item data roles InternalPathRole and UrlRole have been removed, and replaced by a LinkRole (which contains a WLink value instead).

D) Deprecated API

With the introduction of WLink, the following API is being deprecated (although it can be argued that some of these may be kept for convenience):
  • WAbstractArea::setRef(): use WAbstractArea::setLink() instead.
  • WAbstractArea::ref(): use WAbstractArea::link() instead.
  • WAbstractArea::setResource(): use WAbstractArea::setLink() instead.
  • WAbstractArea::resource(): use WAbstractArea::link() instead.
  • WAnchor::setRef(): use WAnchor::setLink() instead.
  • WAnchor::ref(): use WAnchor::link() instead.
  • WAnchor::setResource(): use WAnchor::setLink() instead.
  • WAnchor::resource(): use WAnchor::link() instead.
  • WAnchor::setRefInternalPath(): use WAnchor::setLink() instead.
  • WImage::setImageRef(): use WImage::setImageLink() instead.
  • WImage::imageRef(): use WImage::imageLink() instead.
  • WImage::setResource(): use WImage::setLink() instead.
  • WImage::resource(): use WImage::link() instead.
  • WStandardItem::setInternalPath(): use WStandardItem::setLink() instead.
  • WStandardItem::internalPath(): use WStandardItem::link() instead.
  • WStandardItem::setUrl(): use WStandardItem::setLink() instead.
  • WStandardItem::url(): use WStandardItem::link() instead.
The following classes have been renamed, and the old name is being deprecated:
  • WHTMLMedia is now WAbstractMedia.
  • WHTMLVideo is now WVideo
  • WHTMLAudio is now WAudio

Release 3.1.10 (July 8, 2011)

This release contains a mix of new features and bug fixes

A) New classes:

We have added support for animations to show or hide widgets (used in WWidget::setHidden(), and WStackedWidget). These animations will only be used when the browser supports CSS3 animations (at the moment of writing that includes latest Firefox, Chrome and Safari releases).
Dmitriy Igrishin factored this out of the WFileResource since most of its functionality (continuations, range support) could be generalized to streaming from a std::istream.

B) Main improvements:

Allowing multiple WServer instances.
Apparently for no good reasons at all, some singletons were still around which prevented you from instantiating multiple application servers. Now you can (but only using the built-in httpd) instantiate multiple servers side by side in the same process, which may server the same or different web applications over different ports. A feature example (multiple_servers) shows how that works.
Internal path encoding in WTemplate and WText
The new setInternalPathEncoding() method will, if needed, enable re-encoding of <a> anchors which reference internal paths consistent with how in the current session internal paths need to be dealt with (which depends on whether the browser supports Ajax and HTML5 History).
Since this requires an additional XML parsing step (but the rapidxml parser that is used is ... rapid !), it is off by default.
Like WWidget::findWidget(), but on the whole application, including widgets outside the WApplication::root().
Generates a new session ID for the application. This is useful to prevent session fixation attacks by changing the session ID when a user has authenticated successfully.
This method allows to specify how the browser should preferably show a (non-HTML) resource.
Methods were added to move a row or a column. In addition we added methods to WTableRow and WTableColumn for accessing cells in the given row or column.
Various improvements to allow more flexible access to TinyMCE settings on a per-instance basis.
An additional argument was added which may specify the use of XHTML tooltips, which are implemented using a <div>.
Make insert() and erase() also work for a collection involved in a 1-N relation
Improved modify() behaviour returns a proxy object which marks the the object dirty also from its destructor, avoiding situations where the transaction is flushed during a modification and remainig changes are forgotten.
Added setDirty() and self() methods.
The packaged sqlite3 version was bumped from 3.6.20 to 3.7.6

C) Non-backwards compatible changes

The signature of the virtual method WWidget::setHidden() has changed.
Probably the biggest breaking change since long, this was needed to add support for animations. This will break existing code which specializes the WWidget::setHidden() method. This code should be updated to pass the WAnimation object.

Release 3.1.9 (April 7, 2011)

This release contains mostly bug fixes and quality improvements.

A) New classes:

WAbstractSpinBox, WDoubleSpinBox
Refactored and reimplemented the spinbox control into an integer and floating point version, which may be implemented either using a native HTML5 element or a portable Wt implementation.

B) Main new features in existing classes:

Internal path handling: HTML5 History API
When the browser supports the HTML5 History API, URLs are now the same for plain HTML and Ajax-enabled session (i.e. without the '#' trick). This can improve load time and improves the user-experience.
To avoid problems of resolving resources with relative URLs, a new property 'baseURL' can be used (that can be configured in wt_config.xml), which allows all relative URLs be resolved from the same location.
Internal path handling: no ugly internal paths ('?_=/path')
The configuration option (--docroot) for the built-in httpd allows to specify folders with static paths and when doing so, all other requests are forwarded to the application, which in turn does no longer need to rely on the ugly '?_=' query parameter to encode its internal paths.
WPdfImage, WRasterImage
Improved font support: the library can be optionally built to use libpango for resolving characters to glyphs. This allows text to be rendered using a mix of different fonts that all provide only partial coverage for the entire unicode range. Note that for WPdfImage, this currently requires use of a libharu fork (https://github.com/kdeforche/libharu/tree/)
WAbstractItemView, WTableView and WTreeView
Implementation of setRowHeaderCount() which fixes the number of columns that are used as row headers and remain fixed while scrolling horizontally through the table. This replaces the now deprecated setColumn1Fixed() API.
Several quality improvements: correct rendering of alpha compositing, text rendering by libpango,
The slider has been reimplemented to allow for using either the native HTML5 slider control, or the Wt implementation. The Wt implementation can now also be styled through CSS.
WRun(), WServer::addEntryPoint()
The callback function is now a boost::function<> object, allowing you to bind other variables into the callback function.
A safe method to post events to a session, and a useful alternative to WApplication::UpdateLock. The simplechat and codeview examples were converted to illustrate this method rather than the (dead-lock prone) WApplication::UpdateLock approach.
Implementation of plural string resolution, with locale-dependent rules. The implementation provided by WMessageResourceBundle allows the same kind of expressions as GNU ngettext().
Allows to specify the minimum chart axis resolution (contributed by Gaetano Mendola).
Fixed an issue with internal inconsistencies after transaction rollback.

C) Non-backwards compatible changes

Changed i18n keys for Wt.WDate.Mon-Sun and Wt.Date.Jan-Dec
We were pointed out the fact that the built-in i18n keys for WDate month names had a collision for the month 'May', which had the same key for the abbreviated 3-letter variant as the full length variant. Therefore in this release we reformatted the abbreviated 3-letter variant keys to Wt.WDate.3.Mon-Sun and Wt.WDate.3.Jan-Dec. You will need to update your own languages copies of these (or better, contribute them and we'll maintain them for you!).

D) Android and iPad/iPhone targets

This release contains initial work on supporting Android and iPad/iPhone as targets for deploying Wt applications within a webkit view widget.

For iPad/iPhone, we added a script that builds Wt as an OSX Framework which may be used in XCode to build iOS applications.

For Android, we added support for building the library and examples as shared objects which are packaged together with a small Java project which instantiates a WebView, into standalone APK files.

This is ongoing work. We need to improve support in Wt for Mobile Webkit to make the applications look and behave more as native applications on these devices.

Release 3.1.8 (Feb 4, 2011)

This release contains mostly bug fixes, quality improvements, and a few new features.

A) New classes:

A font metrics class. Font metrics are only available for WPdfImage, and an implementation is planned for WRasterImage.
Render::WTextRenderer, Render::WPdfRenderer
A renderer class for a subset of XHTML, useful for e.g.~generating PDF reports.

B) Main new features in existing classes:

Rendering of header cells is now also delegated and can be customized.
Scroll to a particular item.
Added support for Right-To-Left (mirrored) layouts, typically used with some middle-Eastern languages. In addition to HTML's built-in support for RTL directionality, layout managers, tables and MVC tree/table views render their columns in the opposite order.
WBoxLayout, WGridLayout, WBorderLayout
Empty layout items do longer create padding, and thus padding collapses around empty items (both horizontally and vertically).
Information on the event type may be used during WApplication::notify() for e.g. detecting user activity.
Added support for Google API version 3, alongside version 2.
Added support true type font loading, a UTF8 patch for libharu is pending to enable full unicode support text rendering.
WWidget::setWidth(), WWidget::setHeight()
Convenience methods for resize() for only width or height.
A number of methods to customize the location and look of the legend.
Allow use of a specific X series for each data series in scatter plots.
Dbo::belongsTo(), Dbo::hasMany()
Support for foreign key constraints (NotNull, OnDeleteCascade, etc...).
Can be optionally given a single table name to reread (discard) all object data from a single class/table.
Dbo::sql_value_traits<bool>, Dbo::sql_value_traits<long>
Added mappings for C++ bool and long types.

C) API and other changes:

CORS (Cross-Origin Resource Sharing)
A communication method between browser and server is now chosen based on the needs (same origin or cross-origin), and based on browser support. Cross-Origin requests are now supported for both Ajax and WebSockets, and are are chosen if available and needed, reverting to dynamic script-tags otherwise.
The WApplication::setAjaxMethod() has no effect anymore, and has been deprecated.
Bootstrap process has changed.
While tracking bootstrapping problems on IE8 (resulting in a blank page instead of a shiny app), we not only found a good workaround for that, but also found a way to implement the default bootstrap mode so that the stylesheets are applied before the application is rendered. This solves the annoying flicker you experienced with the default bootstrap mode, and also allows us to remove a number of workarounds for IE. As a result of various cleanups, more CSS stylesheet rules have been pushed out to the external wt.css (theme) stylesheet. If you've created your own theme, you will need to take note.
Wt::WBrushstyle has been renamed to Wt::BrushStyle. This makes it consistent with the naming conventions of other enums. Sorry, our mistake !

Release 3.1.7 (Nov 26, 2010)

This release contains mostly bug fixes, quality improvements, and a few new features.

Note: the package was updated (3.1.7a) on Nov 30 to fix a layouting regression.

A) New classes:

A preview of WebGL support in Wt (work in progress).

B) Main new features in existing classes:

Added API for hiding columns.
WCartesianChart, WPieChart
Added support for ToolTipRole data, using WAbstractArea interactive areas.
Reread all transient objects, as a catch-all solution to stale data (data modified in another session).
Added support for touch and gesture events (Mobile webkit).

C) Misc:

WebSocket protocol support (experimental)
Use of WebSocket for communication between browser and server can now be used, by enabling <web-sockets> in the configuration file (we're likely to turn this on by default in a future version. There is automatic fallback to the current XMLHttpRequest based communication if WebSockets are not available or communication could not be established. WebSockets is only available using the built-in httpd server (which is now also a WebSocket server).
Build improvements
  • Provide a workaround for broken g++ compiler shipped in Ubuntu Maverick
  • Provide support for building without using std::wstring (-DWT_NO_STD_WSTRING) or std::locale (-DWT_NO_STD_LOCALE=OFF) support.

Release 3.1.6 (Oct 29, 2010)

This release contains a healthy mix of bug fixes, quality improvements, and new features. And hopefully no regressions :-)

A) New classes:

A dead-lock avoidance adaptor for a Boost mutex lock, which provides a controlled way of releasing the current application lock.
A progress bar, contributed by Thomas Suckow.
A spin box.
A traits class for customized interpretation of data stored in a boost::any. You can register a new type using registerType<Type>.

B) Main new features in existing classes:

Native support for MSIE 9
MSIE 9 (Beta) is now supported in all its goodness, including support for HTML5 canvas and (almost working) support for SVG.
The lock is now a RIAA lock, getUpdateLock() has been deprecated. The lock needs also to be tested against validity (using operator bool()): when invalid the session that it is trying to lock is being destroyed.
Provide the user with a message to confirm navigating away from the application.
Rather then waiting for the session to expire, an application that is navigated away iis now notified of this and will by default quit().
Can now be used to specify "http-equiv" meta headers too.
I wonder how we ever did without.
WAbstractArea::mouseWheel(), WInteractWidget::mouseWheel(), WMouseEvent::wheelDelta()
Added mouseWheel() event.
Added support for the simultaneous upload of multiple files (HTML5 "multiple") attribute and showing a progress bar to show upload progress.
Returns whether the widget currently has the keyboard focus.
Added events to catch play, pause, play-back progress and volume changes.
WLineEdit, WTextArea
Added currentPosition(), selectionStart(), selectedText(), and hasSelectedText() methods to retrieve the current cursor position and selection.
Utility method to create an anchor that looks like a button, or a button that behaves like an anchor, depending on your point of view. There is also setResource() to set a resource as target.
Added API for upload progress tracking.
Added support for HTTP request byte ranges, and this is now interpreted by both the WFileResource and built-in httpd for static files.
Added setContentLength() which allows you to specify the length of the response in advance, proving a better user experience for large downloads.
Switched to a more complete Boost.Spirit parser for SQL queries, which understands most of the SQL syntax, including functions, "with ... select ... ".
Added support for custom column header names and changing the underlying query using setQuery() while preserving the current column definitions.
Added boost::posix_time::time_duration type support.
Added template specialization for WTime.

Release 3.1.5 (Sep 10, 2010)

This release contains mostly bug fixes.

A) Main Changes

WGridLayout, WBoxLayout
Optimized client-side rendering performance. Previously, every layout manager used would automatically slowdown every event because it would try to relayout each time. This is no longer the case.
The socket notifier has been resurrected (it was in a perpetual state of brokenness) and now works reliably across targets.

B) Changes that may break existing applications:

1) Built-in resource bundles

Starting with this version, Wt uses an internal message resource bundle for the few strings it provides by itself (like for example 'Ok' for the ok button in a WMessageBox, or the days-of-week in WDate). Previously, an ugly API was used in WMessageBox, WCalendar, and WDatePicker using a boolean 'i18n' parameter in the constructor. All this has now been removed, and instead the keys for these built-in strings have been documented. If you were using these classes your application will no longer build, you can simply remove the internationalization parameter and you will need to fix the keys you used for the messages according to the documentation. Any localized strings you use will take precedence over these built-ins. All affected classes (only those listed above actually have changed API and behaviour) are:
the paging tool bar buttons for graceful callback.
because of WDate
WDate and WDateTime
week days, month names
because of WCalendar and for the close button
loading text
save and cancel button text
standard buttons
standard buttons
for the messages they display in case of error

2) Other behavioural changes

Escape will no longer result in the dialog being rejected. You can enable this behaviour using the rejectWhenEscaped() method.

Release 3.1.4 (Aug 13, 2010)

This release contains several new features, but also a few changes that break backwards compatibility (but are unlikely to affect an average application).

A) New classes:

A proxy model that caches editing operations to commit them atomically.
Audio support using the HTML5 audio tag.
A WPaintDevice that writes to Pdf (using libharu).
A WPaintDevice that writes to a Png/Gif (using GraphicsMagick).
ISAPI connector
(Windows only) a connector that implements the Microsoft ISAPI API, to integrate directly into Microsoft IIS. On Windows, this is an alternative deployment option next to the built-in httpd.

B) Main new features in existing classes:

Added support for validators while editing.
Added an appRoot() method this returns the value of the special property "approot" which can in some cases be defined implicitly by a connector (such as ISAPI), and which allows an application to reference working files whereas previously it was assumed that they were in the working directory (CWD).
WEnvironment::agent() and related
Convenience methods that return pre-parsed user agent identification, should you want to differentiate based on browser.
WWidget::addStyleClass(), WWidget::removeStyleClass()
Added addStyleClass() and removeStyleClass() methods.
WMenu, WMenuItem
Added support for closable and disabled items (not complete, CSS is lacking for polished theme). Contributed by Dmitriy Igrishin.
Added support for in-place (destructive) encoding to and decoding from a raw index, making this less of a hassle for View classes.
Added support for row insertion/removal.
Allow usage as an advanced combo-box, with an explicit drop down button and ability to react to a selection.
Support for natural keys (possibly of composite type) next to the built-in surrogate keys.
By specializing this traits class, you can modify the surrogate id field name (or disable it), and the optimistic version lock field name (or disable it).
More robust query parsing (of the 'select' part), including support for "select distinct".
Added editing support (editing the model will modify the queried dbo's).
Added setValue(), create(), add() and remove() methods for modifying queried results.

C) Changes that break existing applications:

This class is now a templated with the class name itself, in order to provide the proper type for the (natural or surrogate) id field for id(). You will need to replace
      class User : public Wt::Dbo { ... }
      class User : public Wt::Dbo<User> { ... }
The toplevel container used by Wt is now given a position: relative style; this was needed to be able to position widgets (such as popups) using position: absolute, but may break application layouts. You can override this CSS style by adding .Wt-domRoot { position: static; } to your application's (internal or external) stylesheet.

Release 3.1.3 (May 20, 2010)

This release several new features, but also a few changes that break backwards compatibility (but are unlikely to affect an average application).

A) New classes:

SignalBase, EventSignalBase
Abstract base classes for signals (these are not actually new, but they were not yet part of the API).
Video support using the HTML5 video tag (work-in-progress).
Class for executing a database call.
Dbo::SqlConnectionPool, Dbo::FixedSqlConnectionPool
Connection pool interface and implementation.
An tabular item model for query results.

B) Main new features in existing classes:

Added methods for editing: editState(), setEditState(), setModelData() and closeEditor().
New editing API: edit(), closeEditor(), saveEditedValue(), setEditOptions(), setEditTriggers().
Graceful degradation support using a paging navigation bar, which may be customized by reimplementing createPageNavigationBar().
WCalendar, WDatePicker
Added setBottom() and setTop() methods to specify a valid range.
Added a mouseDragged() event for responding to mouse moves while a mouse button is down.
Implements editing using a WLineEdit.
Can now be used without a contents stack.
Added API to support dynamic server-side filtering.
New implementation which supports horizontal and vertical virtual scrolling, column resizing, drag and drop, etc... like WTreeView.
Supports now also a shadow effect.
A find() method has been added to refine the query of a many-side relational.
A version() method returns the current version.
An extra template parameter specifies a binding strategy. The default binding strategy is DynamicBinding, which allows reuse of the query object, and provides new API to modify the query: where(), orderBy(), groupBy(), offset(), limit().
Added support for use with a connection pool. Added execute() method to execute an SQL statement.
Built-in httpd
Support for HTTP Range header and partial content serving.

C) Changes that break existing applications:

This traits class has been renamed to query_result_traits and its API has changed considerably. This will only impact when you have implemented a custom traits specialization. The getColumns() method has been replaced with a getFields() method, and the loadValues() method has been renamed to load(). A getValues() method has been added which provides conversion to boost::any's.
This View class was reimplemented to have functionality comparable to WTreeView. In the process, we had to abandon the underlying <table> representation because of rendering issues with Chrome (of all browsers!), although the WTableView documentation specifically promised that we would keep this.

Release 3.1.2 (March 26, 2010)

This release contains mostly bug fixes, and a few new features.

A) New classes:

Class representing a drop shadow effect (see below).
A Postgres backend has landed, contributed by Hilary Cheng.

B) Main new features in existing classes:

WBoxLayout, WGridLayout
Addition of horizontal and vertical splitter support (resize handles to allow the user to adjust the layout), sponsored by Eurofer. The new API methods are setResizable(), setColumnResizable() and setRowResizable()
Improved the API to allow custom cell rendering, and custom handling of selection. We have also made the API for selection consistent with other widgets (like WTreeView), deprecating the old API.
Added toPosixTime() and fromPosixTime() methods to interoperate with boost::posix_time::ptime.
Added a setEmptyText() method to implement a label inside a line edit or text area.
Added a setShadow() method which defines a drop shadow to be used for subsequent drawing actions.
Added a setInternalPath() method which allow a resource to be deployed at a deterministic and "pretty" URL.
Added constructors that take a std::locale for interpreting a narrow string in a given locale.
Added setLayoutSizeAware() and layoutSizeChanged() methods which allow a widget to react to layout size changes.
Added access to the request method().
Added a setStatus() method to modify the response status.
Added support for schema qualified tables, in Session::mapClass() and the joinTable specified in hasMany().
Added API for dropping the schema: dropTables().
Added support for arbitrary queries in Session::query(), including queries that do not return result or do not select from tables.
Allow size suggestion for std::string and WString mappings
Dbo::SqlConnection, Dbo::SqlStatement
Added support for floating point types, binary data (using std::vector<unsigned char>) and date and date/time types.
Added methods for return dialect-specific information.
Added properties API.
Added support for backend-specific type mapping.
(internal) DomElement
Performance improvements in serializing the widgets to HTML and/or JavaScript
Built-in httpd
Added a configuration option --max-request-size to limit the size of a POST instead of the built-in default of 40 MB
Added a configuration option --max-memory-request-size to limit the size of a POST that is handed in-memory. Bigger POSTs are handled using a spool file.

Release 3.1.1 (February 17, 2010)

The minimum boost version is now 1.36.

This release handles mostly bug fixes, with as most visible change an update of the polished theme, which is now considered complete.

A) Security fixes:

Because of the following fixes for security problems, we recommend anyone to upgrade live deployments of his application to the latest version.
Possible XSS vulnerability
Fixed a possible XSS attack where a user follows a link to a Wt web application, taking advantage of unchecked insertions of the URL when redirecting to the canonical page.
Possible UTF-8 vulnerability
Form values and JSignal arguments received from the browser are now checked for sane UTF-8 encoding.

B) New classes:

An optional base class for a database object, providing access to its id() and session().

C) Main new features in existing classes:

Now implements native text rendering on Firefox and latest Chrome and Safari browsers
Added a setEmptyText() method which sets the text to be displayed when value is empty.
Added an exec(WWidget *location, Orientation orientation) method which popups the menu besides another widget.
This class is now also style by the CSS theme.
Avoids now rerendering of already bound widgets when the template is rerendered.
WTree, WTreeNode, WTreeTable, WTreeTableNode
These widgets are now theme-aware, and tree decoration styling is provided by the theme. The setImagePack() APIs are now no-ops
Added positionAt() method which positions a widget (absolutely) besides another widget.
Added a setLabelFont() method.
Added serverName(), serverPort(), path(), pathInfo(), queryString(), urlScheme(), in(), contentType(), contentLength(), userAgent() and clientAddress() methods which expose information form the HTTP request to WResources.

D) Build changes:

This CMake option has been removed, and Mini-XML has been replaced by a modified RapidXML xml parser (mostly because of the hard-to-interpret Mini-XML license), but there are also nice performance improvements.

Release 3.1.0 (December 29, 2009)

This release contains several new features and classes, after a long period of stabilization that happened before the 3.0.0 release.

A) New classes:

A model that provides support for drilling down through columns, supported by WTreeView.
Combines different localized strings implementations.
Combines a calendar date (WDate) and a clock time (WTime).
Use an XHTML fragment as a template, with variables that are place holders for strings or other widgets. See the blog example of how this class can be used to simplify HTML/CSS based layout of widgets and contents.
Represents a clock time (0-24 hours).
An Object Relational Mapping library. See the tutorial here.

B) Main new features in existing classes:

Most inline CSS styles have been pushed out to an external style sheet, which may be themed. The "default" theme provides the old look, while a new "polished" theme provides a less boring (?) look for several widgets (work in progress). The theme can be set using WApplication::setCssTheme(). As a result, you will need to deploy Wt's "resources/" folder, which contains the themes in "resources/themes/", for all but the most trivial applications.
Added a template connect() method which may be given any function object, providing also support for the (future) c++1x lambda functions.
Several optimizations to output more concise JavaScript.
When width and/or height is not set using resize(), the widget will now properly react to layout management when put into a layout manager, triggering a server-side rerendering when needed.
A sliderMoved() signal was added which is fired whenever the slider is moved (but not yet released).
Added a find() method which searches the widget hierachy for a widget with a particular objectName().
Added an addResource() method to bind static resources to particular URLs (i.e. resources that are not bound to a specific session).
Will now properly react to layout management from a layout that is set for a WContainerWidget.
Added changed(), blurred() and focussed() signals.
Added setAutoLimits() and autoLimits() methods to configure which limits are to be determined based on the data, and which are explicitly set.
Added the setHidden() and hidden() methods to enable or disable a data series. Added setBarWidth() and barWidth() methods to set the width of a bar (useful mostly for scatter plots). Added setMarkerSize() and markerSize() methos.
Use MarkerPenColorRole and MarkerBrushColorRole to override colors for makers on a per data point basis. Added mapFromDevice() and mapToDevice() methods for mapping device coordinates to chart coordinates and vice-versa

C) API Changes:

Not really an API change, but the vertical slider is now showing the maximum value at its top side, not its bottom side.
The minimum() and maximum() methods will now return the calculated minimum and maximum value when they are to be automatically calculated based on the data, configured using setAutoLimits()

D) Build changes:

A new configuration option, XML_FEATURES, was added which allows the library to be built without MiniXML (and disabling fatures that require Mini-XML support). This configuration option is likely to be removed again in future versions.
A doc directive was added, which uses doxygen and asciidoc tools to generate the reference documentation and tutorial.
Automated tests were added for non-interactive functionality, and are built by default.

Release 3.0.0 (November 3, 2009)

This release contains mostly bug fixes, build improvements and documentation improvements compared to the latest pre-release (2.99.5).

Most build improvements are related to finding the boost libraries. Previously, Wt used a custom script, since CMake versions < 2.6 did not provide a good enough script for finding boost. Starting with this release, when using CMake 2.6 or later, Wt will use the script that comes with CMake. You can still fall back to the script that comes with Wt, which is still used for older versions of CMake, by defining one of the BOOST_COMPILER or BOOST_VERSION variables.

A) New classes:

No new classes

B) Main new features in existing classes:

It is now possible to have multiple modal dialogs, and nested recursive event loops.
The setDisabled() method moved up from WFormWidget to WWidget.
The exec() method now passes object and event to the JavaScript event handler.

C) API Changes:

The handling of changes to the resource has been sanitized. A new method, setChanged() was added which must be called to notify users of the resource that the resource was changed. In addition to the existing generateUrl() which generates a new URL, a method was added which merely returns the existing URL: url(). With these improvements, a resource can effectively be shared by many view widgets and updated with the minimum of bandwidth usage.

Release 2.99.5 (September 1, 2009)

This release contains mostly bug fixes. The previous release (2.99.4) contains some critical bugs that cause mayhem on IE, and a regression with server push.

Release 2.99.4 (August 27, 2009)

!! This release contains bugs that render it unusable on IE !!

This release contains mostly bug fixes and back-end improvements. The most exciting new feature is the addition of a new bootstrap method, which implements progressive enhancements (starting with a plain HTML page, and then upgrading it to an AJAX page if the browser has support), see also the documentation.

A) New classes:

This is a simple MVC View class that renders tabular data in the most straight forward way using an HTML table element

B) Main new features in existing classes:

Added insert() methods.
Added an enableAjax() method which notifies the application that a session is being enhanced with AJAX capabilities when using the progressive bootstrap method.
Added an enableAjax() method which enhanced the widget with AJAX capabilities when using the progressive bootstrap method.
Add support for custom cursors.
For FastCGI deployments, the proxy process which directs FastCGI requests to the correct session process is now also multi-threaded.

C) API Changes:

The WApplication::notify() behavior changed.
Previously during a request, this method was called multiple times during event propagation and rendering of the application. Now, the method is called exactly once for each request. In this way, it becomes a useful entry point to also manage resource usage during (and inbetween) requests.

Release 2.99.3 (July 24, 2009)

This release contains mostly bug fixes and small feature improvements. The most notable change that might affect existing applications is a simplified internal path API behavior.

A) New classes:

WAbstractItemDelegate and WItemDelegate
WAbstractItemDelegate is a helper class used by WTreeView (and in the future perhaps other view classes) to render contents. The standard implementation, WItemDelegate maintains the default implementation that was previously integrated in WTreeView. The delegate will be responsible for editing features in WTreeView in the future, and in fact, you can already implement a custom item delegate that does editing if you cannot wait for it!
WTestEnvironment is an environment class which is useful for (unit) test-cases: it allows the instantiation of a WApplication so that you may include widgets in unit tests.

B) Main new features in existing classes:

C) API Changes:

change of WApplication::internalPathChanged() semantics.
The old behavior was that a single internal path change caused by the user (e.g. by moving forward/backword through his browser history) would cause repetitive invocations of internalPathChanged() with different arguments. The underlying idea was that this would make it easier to have the handling of internal path changes distributed over different objects. It caused however more problems than it solved. The new behavior is now that it is invoked exactly one time, and the argument is simply the new internal path.

Release 2.99.2 (May 29, 2009)

This release contains mostly build improvements, bug fixes, and API cleanups.

A) New classes:

Client is a utility class to bootstrap a new Wt application.

B) Main new features in existing classes:

Add setFocus() method.
Added an addStretch() method (contributed by David Galicia).
Added a continuation() method.
Add support for tri-state checkboxes. These are also supported by item models and WTreeView.
Support for non-modal dialogs and interactive moving.
New methods setReadOnly() and isReadOnly().
Support a row stretch value of -1, which is like 0 but will still manage the height of cells (allowing their contents to fill the entire cell).
Support update rendering (not erasing the current canvas) using paint flags.

C) API Changes:

WFileUpload::isUploaded() was deprecated
The name was not covering its actual behavior: instead of checking whether a file has been uploaded, it returns whether true when a call to upload() is not needed. You should replace any call to isUploaded() with the new method !canUpload() (note the inversion!.

Release 2.99.1 (Mar 20, 2009)

This release contains only build improvements, bug fixes, and API cleanups.

Release 2.99.0 (Mar 4, 2009)

This release is a preview for Wt 3.0.0. Many things have changed both in the internals and the API. This is the first release that provides several API changes which are not backward compatible (some of which were post-poned until now). Please read the following notes carefully, especially sections C) and D), to understand what changes to expect and how to adapt existing applications.

Support for the C++ boost library < 1.35 has been dropped: Wt now requires at least boost >= 1.35.0.

A) New classes:

WFlags is a utility class that provides a type-safe ORing of enum flags. It is used everywhere in the Wt API where previously an int was used to allow enums to be ORed together.
This is a widget, contributed by Richard Ulrich, that displays a Google map.
Http::Request, Http::Response, Http::ResponseContinuation and Http::UploadedFile
These are utility classes which model an HTTP request and response and that are used in the new WResource API.

B) Main new features in existing classes:

Server-initiated updates (aka "server push") has been reimplemented and now works reliably in all situations, including in the presence of intermediate proxies. The dependency on the 3rd party JS orbited library has been removed and replaced with a simple XHR-based solution.
Various methods were added: id's may be associated with a specific radio buttons, which may be used to identify a particular button.
Is now easier to use because of a sensible default constructor that also creates the line edit using a WDateValidator, and creates the icon which is associated with the popup.
Uses the continuation support in the new WResource API to transmit the file in chunks.
WLength::Auto was added, is a synonym for WLength()
Is now also an MVC View widget, reading its data from a WAbstractItemModel
New method setHeaderCount() to specify the number of first rows or columns that should be rendered as an HTML table header (<th>).

New virtual method rerender() which allows a widget to prepare itself before rendering (and defer internal changes until that time). A widget may ask to be rerendered using askRerender()

Widget no longer inherits from WResource, but instead inherits directly from WObject. It was simply a bad idea, and not useful for anything.

C) Changes that break existing applications:

1) Signals are no longer public members

Instead, they are now accessor member functions: e.g. WInteractWidget::clicked has been renamed to WInteractWidget::clicked(). This has as major benefit that signals can be created on-demand, which leads to drastically lower memory usage and significant speedups especially on embedded systems.

The change requires that everywhere in your code where you access a signal, you will need to change to add parentheses. For consistency, you may also want to use the same convention for your own widget classes that define signals.

2) WResource

The API has been redesigned and greatly simplified. If you are implementing your own resources, then you will need to redesign your implementation. The new API is simpler (requires only one virtual method to be implemented) and more powerful, providing support for continuations to serve large resources without blocking a thread or requiring large memory usage.

In addition, resources have better thread-safety: they are now by default reentrant (requests for a single resource may be handled concurrently) and they are protected from concurrently being destroyed by the main event loop.

3) WValidator

The signature for the virtual validate() method was changed: parameter pos which was ignored anyway has been removed.

4) WEnvironment

The methods getArgument() and arguments() were renamed to respectively getParameter() and getParameterMap(). The signature for getParameter() is also different as it returns a pointer to a string, which is 0 when the parameter is not defined, instead of the olde behaviour of throwing an exception. There is a new method that allows to read all values for a parameter, getParameterValues()

5) WModelIndex

The 20-byte SHA1 hash based internal pointer has been removed again as the object increase and overhead could not be justified.

D) Deprecated API that was removed:

These are API calls that were deprecated in earlier releases, and have now been completely removed from the library:
Use WApplication::internalPath() instead.
Use WApplication::setInternalPath() instead.
Use WApplication::internalPath() instead.
Use WApplication::internalPathChanged() instead.
WRegExpValidator::WRegExpValidator(const boost::regex&)
Use the WRegExpValidator(const WString&) constructor instead.
WPainterPath::drawArc(..., width, height, ...)
An elliptical arc segment could not be support on all devices.
Use WTable::rowCount().
Use WTable::columnCount() instead.
WText::setFormatting() and WText::formatting()
Use WText::setTextFormat() and WText::textFormat() instead.

Release 2.2.3 (Jan 26, 2009)

This release is a maintenance release, with mostly bug fixes and feature improvements.

A) Main new features in existing classes:

const char * data in boost::any is now also supported.
Implemented toRawIndex() and fromRawIndex() so that indexes can be recovered when the model's layout is changed, if the underlying model provides implementations for toRawIndex() and fromRawIndex().
Also supports StyleClassRole data role for items
New method setTitleBarEnabled() to disable the default title bar.
New method removeItem(), only works when rendered as a list.
New method removeTab().
  • New method setColumn1Fixed() to fix the first column while scrolling horizontally through the other columns.
  • New method setColumnFormat() to control formatting of data.
  • New method setColumnBorder() to set the internal column border color.
  • New method setColumnResizeEnabled() to disable resize handles.
  • The view now also reacts correctly to insertion and removal of model columns.

B) New examples

An example that demonstrates how to implement a custom abstract item model.
An example that demonstrates drag and drop support in WTreeView.

C) Changes that break backward compatibility

useStyleSheet() only supports a subset of IE condition strings, since the string is now parsed by Wt rather than by IE (when dynamically loading stylesheets, the comment-syntax does not work reliably).

Release 2.2.2 (Dec 1, 2008)

As of now, we will also be listing noteworthy new API features, even if they are no concern for backwards compatibility.

A) New classes:

WPopupMenu, WPopupMenuItem:
A popup menu, which you would typically use to present a context menu.
WAbstractProxyModel, WSortFilterProxyModel:
Proxy models, which present data from a source model in a different way.
WLoadingIndicator, WDefaultLoadingIndicator, WOverlayLoadingIndicator:
Customizable loading indicators.

B) Main new features in existing classes:

WTreeView, WAbstractItemModel:
The WAbstractItemModel interface was extended to allow handling of drag & drop events, and WTreeView now is able to start dragging and handle dropping of item selections and other data.
You can now pass the original (keyboard/mouse) JavaScript event as a parameter to custom signals.
access mouse event in itemClicked, doubleClicked and mouseWentDown signals.
Support for widget-set mode, allowing a Wt application to be embedded in an existing web page/application.

C) Changes that break backward compatibility

This release does not contain changes that break existing applications.

Release 2.2.1 (Nov 3, 2008)

This release is as usually a mix of bug fixes, improvements and new features.

We have made a significant change to the MVC system, which will break existing program code in case you have implemented your own models (i.e. deriving from WAbstractItemModel) or views widgets (i.e. components that listen to model changes).

The WAbstractItemModel interface was changed to support hierarchical models. This means that most methods will now take an extra parameter that specifies the parent WModelIndex, and also all signals have now this extra parameter. Because the parameter has a default value of WModelIndex() which corresponds to the top level parent, the API is largely backwards compatible when merely using the model. It is only those classes that reimplement the interface, or listen to signal events, that are affected.

The immediate benefit of the new WAbstracItemModel interface is that it allows us to implement View widgets like the new WTreeView widget.

Release 2.2.0 (Sept 12, 2008)

This release has a rather substantial rewrite (and simplification) of Wt's bootstrapping process. In the past, Wt used a frameset trick to be able to load the AJAX-based skeleton when JavaScript was available. Instead, now, the entire AJAX-based stuff is loaded directly into the bootstrap page. A benefit of the new approach is that we avoid iframe tricks, which have been deprecated from strict HTML and XHTML. But, it was in fact motivated in the first place to support all major browsers for a new internal path API. This new API allows to fully support URL changes and bookmarks in a unified way (i.e. it works equally when the browser supports AJAX, no JavaScript, or is a bot such as google bot).

As a consequence, this release contains the following changes that may break your application:

  • WMenu::enableBrowserHistory() and WMenu::browserHistoryId() have been removed, use the new methods WMenu::setInternalPathEnabled() and WMenu::setInternalBasePath()
  • WMenuItem has been reorganized, and if you have specialized WMenuItem you will need to adapt your reimplementation to the new virtual interface. In the new interface, you need to reimplement WMenuItem::createItemWidget() and WMenuItem::updateItemWidget() allowing you to react to item changes (internal path or text). The default implementation now always uses a WAnchor.
  • WApplication::setState(), WApplication::state() and WApplication::stateChanged have been deprecated. It is strongly advised that you use the new internal path API instead. This does require you to treat different parts of the state as a file hierarchy. See the WApplication::setInternalPath() documentation.

The following methods have been deprecated (but are still supported):

  • WTable::numRows() has been renamed to WTable::rowCount().
  • WTable::numColumns() has been renamed to WTable::columnCount().

Release 2.1.5 (July 25, 2008)

Wt now installs its include files in a Wt/ subdirectory. You may want to change your build files to pick up this new include directory, or, change your code to scope the include files to look like #include<Wt/WLineEdit> instead of #include<WLineEdit>

This release contains the following changes that may break your application:

  • WText will validate XHTML text when it is set to the widget. The old behaviour was to validate only before rendering. The change was needed to be able to react to XML parse errors. As a consequence if you are creating a WText with text that is not valid XML, followed by a call setFormatting(WText::PlainFormatting), you should change this now to use the new WText constructor which takes the TextFormat as a new argument: new WText(text, Wt::PlainText, parentWidget)
  • WContainerWidget::setLayout(WLayout *layout, bool fitWidth, bool fitHeight) has been replaced with the more generic WContainerWidget::setLayout(WLayout *layout, int alignment).

The following methods and enumerations have been deprecated (but are still supported):

  • enum WText::Formatting has been renamed to Wt::TextFormat. The old values map as follows on new values:
    • WText::XHTMLFormatting becomes Wt::XHTMLText;
    • WText::XHTMLUnsafeFormatting becomes Wt::XHTMLUnsafeText
    • WText::PlainFormatting becomes Wt::PlainText
  • WText::setFormatting() has been renamed to WText::setTextFormat() and WText::formatting() has been renamed to WText::textFormat().

Release 2.1.4 (July 4, 2008)

The following has changed for building Wt:

  • The CMake variable CONFIGURATION (which defaulted to /etc/wt/wt_config.xml) is no longer used, but instead there is now a CONFIGDIR (/etc/wt/) which is used to store configuration files.

The following has changed in the wt_config.xml file:

  • The <valgrind-path> setting for the FCGI connector may now be a command-line including arguments

This release should not contain changes that may break your application.

Release 2.1.3 (May 20, 2008)

This release should not contain changes that may break your application.

Release 2.1.2 (April 14, 2008)

The following changes may break your application build:

  • WTreeNode::expanded() has been renamed to WTreeNode::isExpanded().

Release 2.1.1 (April 10, 2008)

This release should not break any of your applications, but we did deprecate some methods and enumeration types. You are advised to migrate to the replacements methods since we will discontinue support for the older ones in the future.

The following methods and enumerations have been deprecated:

  • enum SelectionUnit has been renamed to SelectionBehavior. The old values map as follows on new values: CellSelection becomes SelectItems; RowSelection becomes SelectRows.
  • WWidget::setOffset(int sides, WLength) is deprecated, and the new method is WWidget::setOffsets(WLength, int sides): the argument order has been switched to be consistent with the method signature of setMargin() and setPadding().
  • WResource::suggestFilename() has been renamed to WResource::suggestFileName().

The following changes affect run-time behaviour:

  • WTreeNode now supports a policy for when to show a child count indication. The old behaviour was to always show the child count. Now, by default this option is disabled. Use WTreeNode::setChildCountPolicy(Enabled) to get the old behaviour back, if you wish.

Release 2.1.0

The library dependencies have changed slightly.

To build Wt 2.1.0, you need:

  • CMake 2.4 or later
  • boost 1.34.1 (boost 1.33.1 might should still work, but is not recommended)
  • asio 0.3.9: either the boost or non-boost version (only for the http connector)
  • optionally, openssl for HTTPS support (only for the http connector)
  • optionally, libz for gzip compression support (only for the http connector)
  • fcgi library, including C++ bindings (libfcgi++)(only for the fcgi connector)

Furthermore, the Wt::Ext library has been upgraded and now wraps around the extjs 2.x library, instead of extjs 1.x.

Some API changes may need a porting effort:

  • Ext::ProgressDialog: doesn't show by default, you need to call show() to show the dialog.
  • Ext::ContentPanel, Ext::BorderLayout have been removed. They have been replaced with a stand-alone layout system, that may manage contents in an Ext::Container. The layout system provides WBorderLayout and several other layout managers.
  • WSignalMapper has been expanded to allow mapping of signals with an extra argument, which is passed to the mapped signal. Because of this, the signature of the class has been expanded with an extra template argument. If you have forward declarations to WSignalMapper, you will need to modify these too (or simply include WSignalMapper).
  • WAnchor: no longer uses a WLabel internally, and the label-related methods have been removed.

Release 2.0.5

  • WDialog (and WMessageBox) usage changed, and is now more like Qt. When you are not using WDialog::exec() or WMessageBox::show(...), then you must explictly show() the dialog to show it. You can now also hide() the dialog if you want.
  • Moved several enums from within classes to the Wt namespace. This is likely to break your code at compile time when you are using one. The fix is to remove the class scope from the enum type or value.
    • WScrollArea::Orientation -> Wt::Orientation
    • WMenu::Orientation -> Wt::Orientation
    • WMessageBox::StandardButton -> Wt::StandardButton
    • WMessageBox::Icon -> Wt::Icon

Release 2.0.4

Important: 2.0.4a contains a fix for a bug introduced in 2.0.4 that reset the deploy-path in wthttpd.

This release adds a few new features:

  • WComboBox (and WSelectionBox) now use a WAbstractItemModel in a more flexible model/view system.
  • Stylesheets may be browser-conditional (by Patrick Fischer)
  • wthttpd may serve custom error pages (by Patrick Fischer)
  • WResource can now access HTTP GET or POST query arguments. This will break your code (at compile time) if you have implemented your own WResource, since the signature of the streamResourceData() method has been changed to pass the arguments map as a second parameter.

Release 2.0.1

This release fixes some build-related problems, as well as smaller bugs. The main improvement in this release is related to use of Wt in resource-constrained embedded systems.

The most visible change is that the dependency on the Xerces C++ XML library was dropped in favour of the much smaller Mini-XML library. The draw-back is a reduction of supported character encodings to only UTF8 and UTF16, next to the default locale character encoding (which is typically an 8-bit flavour).

When using the built-in httpd, you can now disable support for SSL at compile time, freeing a number of SSL-related dependencies.

In the API, more comparison operators (== and !=) were added to WString, and a WViewWidget was added for simple MVC widgets (with the main purpose to reduce session-state at the server).

Release 2.0.0

This release contains numerous changes which are likely to cause some porting effort for Wt 1.1.x applications to work properly.

If you are upgrading from a 1.99.x release, you will notice that some of these notes have actually evolved, especially with respect to WString and unicode support.

Here is a list of changes with respect to Wt 1.1.x that are likely to require your attention, and some tips on how to do the porting.

1) Namespace Wt

All Wt classes are now inside the namespace Wt.

To handle this change, you will need to:

  • Wrap forward declarations to Wt widgets in header files inside a Wt namespace, or #include <WFwdDeclarations>
  • and scope all Wt classes with Wt::,
  • or import the Wt namespace: using namespace Wt;

2) WString

Previously, most widgets offered double methods that either used a std::string for literal text, or a WMessage for localized text.

In the new release, widgets use Wt::WString for both literal and localized text. WString offers unicode support for both literal as well as localized text. To create a literal string, simply assign or construct a Wt::WString from that string. The strings supported or both narrow and wide C and C++ strings. UTF8 encoded narrow strings may also be converted. To create a localized string, use one of the static methods WString::tr(const std::string key) and WWidget::tr(const std::string key).

To help with legacy code, WMessage is now a typedef for WString, but is deprecated and should not be used in new code. Unfortunately, the constructors WMessage(const char *text) and WMessage(const std::string text), changed meaning! While previously they took a key to construct a localized message, they now take a literal text (the exact opposite!), since they are in fact plain WString() constructors. As a consequence your application will display key values instead of resolving those values (but will not break entirely).

The new approach offers the benefit of only requiring one method signature for both literal and localizable text. This not only simplifies our work, but more importantly by using WString for displayed text in the API of your own widgets, localization (including the automatic language switching) comes automatically and is decided on by the user of your widget.

Fortunately, there is a straightforward trick to handle most consequences of this change:

  • Replace WMessage(...) with tr(...),
  • add .value() when using the result of functions such as WText::text(),
  • change your own classes to use WString wherever they expect some text that will be displayed, instead of std::string or WMessage.

3) Wide string API

Since Wt 2.0.0, the API for Wt has been changed to use WString instead of C++ narrow strings. WString supports both narrow and wide strings, and provides conversion between both. It does not provide string operations, however, and instead acts as a string container. You should convert to a C++ string type to perform operations. You should also not use WString outside of the user interface part of your application.

4) No more wmain()

Previously, the Wt library implemented the main(int argc, char **argv) function, and called a wmain() function which created the WApplication instance.

Wt 2.0.0 allows multiple applications to run within a single process. Therefore, the WApplication::exec() approach was no longer feasible. The new approach requires that:

  • your main function should look like this:
    int main(int argc, char **argv)
      return Wt::WRun(argc, argv, &createApplication);
  • where createApplication is a function of the following signature:
    Wt::WApplication *createApplication(const Wt::WEnvironment& env)
      // return a new application object.

5) Configuration in /etc/wt/wt_config.xml

Wt 2.0.0 uses a configuration file for a number of settings that could previously be configured at build time of the library, or in the API. The latter functions are:

  • WApplication::setMaximumRquestSize()
  • WApplication::setIdleTimeout()

6) Removed obsolete classes

Wt 2.0.0 removed a number of classes that were still in the widget tree, but have been obsoleted by more flexible classes:

  • WAbstractTab, WButtonTab, and WTabWidget are obsoleted by the more flexible WMenu.

7) Deprecate boost::regex from WRegExpValidator API

The constructor and methods that takes a boost::regex object in the WRegExpValidator API have been deprecated, to remove the dependency on boost from the public API. You should consider the std::string based constructor and method instead.

8) WObject::emit() has been removed.

Since Wt 1.99.1, we have removed WObject::emit() function. Instead, you may simply call the signal with its arguments, or use the explicit emit method (recommended).

To adapt your code, you should:

  • Replace all emit(MySignal(...)) with MySignal(...) or MySignal.emit(...)

9) WResource::streamResourceData() signature has changed.

Since Wt 2.0.0, WResource::streamResourceData() returns a boolean value which indicates if all data has been streamed. If you have reimplemented WResource for your applications, you must update the signature and return true.

The change is relevant only within the new server-push support that is now in Wt 2.0.0. This allows you to continuously append to the content of a resource.

10) Rename of WJavascriptSlot to JSlot.

Release 1.1.7

This release contains lots of additions and improvements, but should be completely backwards-compatible.

Release 1.1.6

There is one change which will impact the behaviour of current applications: Currently, on exit, by default the last widget updates are shown. So, no more good-bye message. This changes slightly when one needs to redirect() to a new location: not when WApplication::exec() returns, but during the same event handling as when calling WApplication::quit().

Release 1.1.5

Nothing special...

Release 1.1.4

Changes to impact everybody, since the previous release:
  • The dependency for libxml++ (and its large number of dependencies) has been dropped, and replaced by Xerces-C++ (which has no further dependencies).
  • Wt programs need to link against libwtfcgi.so, instead of libwt.so. In the future Wt will also support different web-connector systems besides FastCGI.
  • The signatures of wmain() and WApplication constructor have changed: new signatures are:
    • int wmain(const WEnvironment& env)
    • WApplication::WApplication(const WEnvironment& env)

Other changes:

  • Support for unicode is implemented, but perhaps needs more testing by non-Western people ? Only UTF-8 is supported currently.
  • Addition of a WTimer class -- see mission example.
  • Many bug fixes which should make Wt more robust against illegal CGI requests (which are ignored), and now Wt should exit cleanly in more (all?) circumstances.
  • Addition of feed-back for pending AJAX requests (does not work yet on IE).
  • Support for style sheets is improved: now inline decoration styles will override style sheet styles. See hangman or treelist examples.
  • The browser can be redirected to a new page. This is useful when the application is terminated -- or to change during the application from HTTP to HTTPS and back.
  • WValidationStatus API has changed -- less complicated now.