# 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 3.3.4 (Mar 25, 2015)

This release has a focus on bug fixes but also one or two new 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.
WIdentityProxyModel
  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.
Chart::WAbstractChart::setAutoLayoutEnabled()
  Until now, you were responsible for configuring the padding around the chart area to accomodate 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).
Chart::WCartesianChart::setAxis()
  Whereas previously a chart axis was a "value class", it is now a proper polyymorphic 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.
  - setPointSprite(): ability to define sprites for drawing a data series
  - pickSurface(): find out which points on a surface are under a given pixel
  - pickBar(): find out which points on a bar on are under a given pixel.
  - setIsoLevels(): draw iso lines (on the ground plane of the chart) corresponding to selected z values.
  - setClippingLinesEnabled(): ability to clip and optionally draw clipping planes
  - setIntersectionsEnabled(): ability to draw surface-surface intersection lines.

## Release 3.3.3 (May 27, 2014)

This release has a focus on bug fixes but also one or two new 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.
WWidget::setDeferredToolTip()
  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.
WLineEdit::setInputMask()
  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.
Dbo::JsonSerializer
  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:

WBootstrapTheme
  Support for bootstrap version 3 was added, so now you have the choice between botstrap 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.
WGLWidget
  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.
WRasterImage
  Next to the GraphicsMagick-based implementation, a skia-based implementation has been added (which provides much higher performance most notably on Windows platforms).
WString
  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:

WLocalDateTime
  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:

WComboBox
  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.
WDialog
  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).
WMessageBox
  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!
WTextEdit
  We've added support for TinyMCE 4.
Signal
  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 much improvemed table rendering (including border-collapse border model and repeated table headers), relative/absolute positioning, and page-break-before/after support.
Auth::AbstractUserDatabase
  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).
Dbo::Query
  Added a reset() function which resets previous bound arguments.
Dbo::QueryModel
  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.
WMessageBox
  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 focusses 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 stlesheets 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
WDateEdit
  Functionally almost the same as a WDatePicker, this class specializes WLineEdit and is thus a WFormWidget, making it much easier to use in WTemplateFormView.
WLocale
  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.
WNavigationBar
  A navigation bar styles a menu as a typical top-level bar (currently only styled in the Bootstrap Theme).
WPopupWidget
  A base class to simplify the creation of popup widgets that typically assist in editing or provide circumstancial information for another widget.
WSplitButton
  A split button, which combines a button and a popup menu (currently only styled in the Bootstrap Theme).
WToolBar
  A button tool bar (currently only styled in the Bootstrap Theme)
Dbo::MySQL
  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:

Mail::Message
  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.
WDialog
  Addition of a footer() method that returns a container for dialog footer elements, typically buttons.
WFormModel
  Addition of a validator() function that returns the validator for a field set using setValidator(),
WGLWidget
  Support for binary transfers which avoids serialization and deserialization of floats to text.
WPushButton
  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().
WStackedWidget
  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.
WStringListModel
  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.
WTemplate
  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.
WTemplateFormView
  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

WMenuItem
  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.
WApplication::locale()
  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.
WCalendar
  The markup for this class has changed, and thus customized CSS will need to be updated.
WPopupMenuItem
  The popup menu item class has been merged with WMenuItem (and WPopupMenu is now a specialized WMenu). This should not have noticable 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

Dbo::backend::Sqlite3

  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:

WSslInfo
  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).
Wt::Dbo::weak_ptr
  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 reimplement, to address various issues with the old implementation, including API (in particular the wonked 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.

WAbstractItemView

  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.

WInteractWidget
  A new method setMouseOverDelay() allows to specify a delay for generating the mouseWentOver() event.
Auth::AbstractUserDatabase
  A new method deleteUser() was added, which deletes a user and all related authentication information.
Chart::WCartesianChart
  A new method setAxisPadding() was added, which configures the amount of adding between the chart area and the axes.
Chart::WDataSeries
  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 perferred 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'ld 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:

WFormModel
  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.
WReadOnlyProxyModel
  A proxy model class which allows to share a source model read-only between multiple sessions.
WTemplateFormView
  A WTemplate-based standard view implementation that works in conjunction with WFormModel.
Auth::AuthModel
  A model that implements authentication logic.
Auth::FacebookService
  An OAuth-2.0 based authentication service implementation for Facebook.
Wt::Utils
  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:

WApplication
  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.
Chart::WAxis
  DateScale and DateTimeScale axes have improved auto-configuration of limits and timesteps, now taking into account the resolution.
Dbo::Transaction
  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 uncomitted transaction would always rollback() on destruction.
Dbo::ptr
  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

WTextEdit
  Due to backwards incompatiblity of IE9, we now require the latest version of TinyMCE (3.5b1 or later).
Auth::AuthWidget
  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().
Auth::AbstractPasswordService::AbstractStrengthValidator
  The API was simplified to be less unorthodox: validate() now returns a Result that contains all the information for it.
Http::Client
  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 verifiation, 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:

WException
  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.
WIOService
  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.
WStringStream
  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.
Dbo::Firebird
  Lukasz Matuszewski contributed a Firebird backend implementation, thanks !

### C) Main improvements:

WAbstractItemView
  Added a setHeaderWordWrap() method which configures header text word wrapping, and changed setHeaderAlignemnt() 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.
WApplication
  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 acceptible time (e.g. 1 second). This effectively stalls the response to the current request, but avoids blocking threads in the process.
WDialog
  Added setClosable(), which adds a close icon into the title bar.
WFormWidget
  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.
WLogger
  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 debuggin 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.
WTemplate
  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").
Dbo::collection<T>
  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).
Configuration
  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.
WValidator
  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.
WTestEnvironment
  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 fournished 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:

WLink
  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 depricated).
WMediaPlayer
  A media player has been added which provides a unified framework for playing audio and video, and which deals with cross-browser issues (chosing 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).
WDialog
  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.
Dbo::Session
  The load() method has an additional, optional parameter, to force rereading the copy from the database.
Dbo::collection<C>
  Added a count() method which uses a query to determine whether the collection contains an element.
Test::WTestEnvironment
  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:

WAnimation
  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).
WStreamResource
  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 reencoding 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.
WApplication::findWidget()
  Like WWidget::findWidget(), but on the whole application, including widgets outside the WApplication::root().
WApplication::changeSessionId()
  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.
WResource::setDispositionType()
  This method allows to specify how the browser should preferably show a (non-HTML) resource.
WTable
  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.
WTextEdit
  Various improvements to allow more flexible access to TinyMCE settings on a per-instance basis.
WWidget::setToolTip()
  An additional argument was added which may specify the use of XHTML tooltips, which are implemented using a <div>.
Dbo::collection<T>
  Make insert() and erase() also work for a collection involved in a 1-N relation
Dbo::ptr<C>
  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.
Dbo::Dbo<C>
  Added setDirty() and self() methods.
Dbo::backend::Sqlite3
  The packaged sqlite3 version was bumped from 3.6.20 to 3.7.6

### C) Non-backwwards 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 horiziontally through the table. This replaces the now deprecated setColumn1Fixed() API.
WRasterImage
  Several quality improvements: correct rendering of alpha compositing, text rendering by libpango,
WSlider
  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.
WServer::post()
  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.
WString::trn()
  Implementation of plural string resolution, with locale-dependent rules. The implementation provided by WMessageResourceBundle allows the same kind of expressions as GNU ngettext().
Chart::WAxis::setResolution()
  Allows to specify the minimum chart axis resolution (contributed by Gaetano Mendola).
Dbo::Transaction
  Fixed an issue with internal inconsistencies after transaction rollback.

### C) Non-backwwards 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:

WFontMetrics
  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:

WAbstractItemView::setHeaderItemDelegate()
  Rendering of header cells is now also delegated and can be customized.
WAbstractItemView::scrollTo()
  Scroll to a particular item.
WApplication::setLayoutDirection()
  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).
WEvent::eventType()
  Information on the event type may be used during WApplication::notify() for e.g. detecting user activity.
WGoogleMap
  Added support for Google API version 3, alongside version 2.
WPdfImage
  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.
Chart::WCartesianChart
  A number of methods to customize the location and look of the legend.
Chart::WDataSeries::setXSeriesColumn()
  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...).
Dbo::Session::rereadAll()
  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::BrushStyle
  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:

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

### B) Main new features in existing classes:

WAbstractItemView
  Added API for hiding columns.
WCartesianChart, WPieChart
  Added support for ToolTipRole data, using WAbstractArea interactive areas.
Dbo::Session::rereadAll()
  Reread all transient objects, as a catch-all solution to stale data (data modified in another session).
WInteractWidget
  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:

SyncLock<Lock>
  A dead-lock avoidance adaptor for a Boost mutex lock, which provides a controlled way of releasing the current application lock.
WProgressBar
  A progress bar, contributed by Thomas Suckow.
WSpinBox
  A spin box.
boost_any_traits<Type>
  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.
WApplication::UpdateLock
  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.
WApplication::setConfirmCloseMessage()
  Provide the user with a message to confirm navigating away from the application.
WApplication::unload()
  Rather then waiting for the session to expire, an application that is navigated away iis now notified of this and will by default `quit()`.
WApplication::addMetaHeader()
  Can now be used to specify "http-equiv" meta headers too.
WDatePicker::changed()
  I wonder how we ever did without.
WAbstractArea::mouseWheel(), WInteractWidget::mouseWheel(), WMouseEvent::wheelDelta()
  Added mouseWheel() event.
WFileUpload
  Added support for the simultaneous upload of multiple files (HTML5 "multiple") attribute and showing a progress bar to show upload progress.
WFormWidget::hasFocus()
  Returns whether the widget currently has the keyboard focus.
WHTML5Media
  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.
WPushButton::setRef()
  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.
WResource
  Added API for upload progress tracking.
Http::Request
  Added support for HTTP request byte ranges, and this is now interpreted by both the WFileResource and built-in httpd for static files.
Http::Response
  Added `setContentLength()` which allows you to specify the lenght of the response in advance, proving a better user experience for large downloads.
Dbo::Session::query()
  Switched to a more complete Boost.Spirit parser for SQL queries, which understands most of the SQL syntax, including functions, "with ... select ... ".
Dbo::QueryModel
  Added support for custom column header names and changing the undelrying query using setQuery() while preserving the current column definitions.
Dbo::SqlStatement
  Added boost::posix_time::time_duration type support.
Dbo::sql_value_traits<WTime>
  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.
WSocketNotifier
  The socket notifier has been resurrected (it was in an perpetual state of brokeness) 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:

WAbstractItemView
  the paging tool bar buttons for graceful callback.
WCalendar
  because of WDate
WDate and WDateTime
  week days, month names
WDatePicker
  because of WCalendar and for the close button
WDefaultLoadingIndicator
  loading text
WInPlaceEdit
  save and cancel button text
WMessageBox
  standard buttons
WLoadingIndicator
  standard buttons
Validators
  for the messages they display in case of error

#### 2) Other behavioural changes

WDialog
  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:

WBatchEditProxyModel
  A proxy model that caches editing operations to commit them atomically.
WHTML5Audio
  Audio support using the HTML5 audio tag.
WPdfImage
  A WPaintDevice that writes to Pdf (using libharu).
WRasterImage
  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:

WAbstractItemView
  Added support for validators while editing.
WApplication
  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.
WModelIndex
  Added support for in-place (destructive) encoding to and decoding from a raw index, making this less of a hassle for View classes.
WSortFilterProxyModel
  Added support for row insertion/removal.
WSuggestionPopup
  Allow usage as an advanced combo-box, with an explicit drop down button and ability to react to a selection.
Dbo::id()
  Support for natural keys (possibly of composite type) next to the built-in surrogate keys.
Dbo::dbo_traits<C>
  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).
Dbo::Session::query()
  More robust query parsing (of the 'select' part), including support for "select distinct".
Dbo::QueryModel
  Added editing support (editing the model will modify the queried dbo's).
Dbo::query_result_traits<C>
  Added setValue(), create(), add() and remove() methods for modifying queried results.

### C) Changes that break existing applications:

Dbo::Dbo
  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 { ... }

  with

            class User : public Wt::Dbo<User> { ... }

CSS
  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).
WHTML5Video
  Video support using the HTML5 video tag (work-in-progress).
Dbo::Call
  Class for executing a database call.
Dbo::SqlConnectionPool, Dbo::FixedSqlConnectionPool
  Connection pool interface and implementation.
Dbo::QueryModel
  An tabular item model for query results.

### B) Main new features in existing classes:

WAbstractItemDelegate
  Added methods for editing: editState(), setEditState(), setModelData() and closeEditor().
WAbstractItemView
  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.
WInteractWidget
  Added a mouseDragged() event for responding to mouse moves while a mouse button is down.
WItemDelegate
  Implements editing using a WLineEdit.
WMenu
  Can now be used without a contents stack.
WSuggestionPopup
  Added API to support dynamic server-side filtering.
WTableView
  New implementation which supports horizontal and vertical virtual scrolling, column resizing, drag and drop, etc... like WTreeView.
Chart::WPieChart
  Supports now also a shadow effect.
Dbo::collection
  A find() method has been added to refine the query of a many-side relational.
Dbo::ptr
  A version() method returns the current version.
Dbo::Query
  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().
Dbo::Session
  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 servering.

### C) Changes that break existing applications:

Dbo::sql_result_traits
  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.
WTableView
  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:

WShadow
  Class representing a drop shadow effect (see below).
Dbo/backend/Postgres
  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()
WCalendar
  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.
WDateTime
  Added toPosixTime() and fromPosixTime() methods to interoperate with `boost::posix_time::ptime`.
WFormWidget
  Added a setEmptyText() method to implement a label inside a line edit or text area.
WPainter
  Added a setShadow() method which defines a drop shadow to be used for subsequent drawing actions.
WResource
  Added a setInternalPath() method which allow a resource to be deployed at a deterministic and "pretty" URL.
WString
  Added constructors that take a std::locale for interpreting a narrow string in a given locale.
WWidget
  Added setLayoutSizeAware() and layoutSizeChanged() methods which allow a widget to react to layout size changes.
Http::Request
  Added access to the request method().
Http::Response
  Added a setStatus() method to modify the response status.
Dbo::Session
  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.
Dbo::field()
  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.
Dbo::sql_value_traits
  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:

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

### C) Main new features in existing classes:

WCanvasPaintDevice
  Now implements native text rendering on Firefox and latest Chrome and Safari browsers
WInPlaceEdit
  Added a setEmptyText() method which sets the text to be displayed when value is empty.
WPopopMenu
  Added an exec(WWidget *location, Orientation orientation) method which popups the menu besides another widget.
WSuggestionPopup
  This class is now also style by the CSS theme.
WTemplate
  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
WWidget
  Added positionAt() method which positions a widget (absolutely) besides another widget.
Chart/WAxis>
  Added a setLabelFont() method.
Http/Request
  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:

XML_FEATURES
  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:

WAggregateProxyModel
  A model that provides support for drilling down through columns, supported by WTreeView.
WCombinedLocalizedStrings
  Combines different localized strings implementations.
WDateTime
  Combines a calendar date (WDate) and a clock time (WTime).
WTemplate
  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.
WTime
  Represents a clock time (0-24 hours).
Wt::Dbo
  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.

Signal
  Added a template connect() method which may be given any function object, providing also support for the (future) c++1x lambda functions.
WCanvasDevice
  Several optimizations to output more concise JavaScript.
WPaintedWidget
  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.
WSlider
  A sliderMoved() signal was added which is fired whenever the slider is moved (but not yet released).
WWidget
  Added a find() method which searches the widget hierachy for a widget with a particular objectName().
WServer
  Added an addResource() method to bind static resources to particular URLs (i.e. resources that are not bound to a specific session).
Ext::Container
  Will now properly react to layout management from a layout that is set for a WContainerWidget.
Ext::FormField
  Added changed(), blurred() and focussed() signals.
Chart::WAxis
  Added setAutoLimits() and autoLimits() methods to configure which limits are to be determined based on the data, and which are explicitly set.
Chart::WDataSeries
  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.
Chart::WCartesianChart
  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:

WSlider
  Not really an API change, but the vertical slider is now showing the maximum value at its top side, not its bottom side.
Chart::WAxis
  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:

XML_FEATURES
  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.
Documentation
  A `doc` directive was added, which uses doxygen and asciidoc tools to generate the reference documentation and tutorial.
Tests
  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:

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

### C) API Changes:

WResource
  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 effictively 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:

WTableView
  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:

Ext::ToolBar
  Added insert() methods.
WApplication
  Added an enableAjax() method which notifies the application that a session is being enhanced with AJAX capabilities when using the progressive bootstrap method.
WWidget
  Added an enableAjax() method which enhanced the widget with AJAX capabilities when using the progressive bootstrap method.
WCssDecorationStyle
  Add support for custom cursors.
WServer
  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!
Test/WTestEnvironment
  `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:

Http/Client
  `Client` is a utility class to bootstrap a new Wt application.

### B) Main new features in existing classes:

Ext::FormField
  Add setFocus() method.
Ext::ToolBar
  Added an addStretch() method (contributed by David Galicia).
Http::Response
  Added a continuation() method.
WCheckBox
  Add support for tri-state checkboxes. These are also supported by item models and WTreeView.
WDialog
  Support for non-modal dialogs and interactive moving.
WFormWidget
  New methods setReadOnly() and isReadOnly().
WGridLayout
  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).
WPaintDevice
  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
  `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.
WGoogleMap
  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:

WApplication::enableUpdates()
  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.
WButtonGroup
  Various methods were added: id's may be associated with a specific radio buttons, which may be used to identify a particular button.
WDatePicker
  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.
WFileResource
  Uses the continuation support in the new `WResource` API to transmit the file in chunks.
WLength
  WLength::Auto was added, is a synonym for WLength()
WSuggestionPopup
  Is now also an MVC View widget, reading its data from a `WAbstractItemModel`
WTable
  New method setHeaderCount() to specify the number of first rows or columns that should be rendered as an HTML table header (`<th>`).
WWidget

  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 signifcant 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:

`WApplication::applicationName()`
  Use WApplication::internalPath() instead.
`WApplication::setState()`
  Use WApplication::setInternalPath() instead.
`WApplication::state()`
  Use WApplication::internalPath() instead.
`WApplication::stateChanged`
  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.
`WTable::numRows()`
  Use WTable::rowCount().
`WTable::numColumns()`
  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:

WAbstractItemModel:
  `const char *` data in `boost::any` is now also supported.
WAbstractProxyModel:
  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()`.
WComboBox:
  Also supports `StyleClassRole` data role for items
WDialog:
  New method `setTitleBarEnabled()` to disable the default title bar.
WMenu:
  New method `removeItem()`, only works when rendered as a list.
WTabWidget:
  New method `removeTab()`.
WTreeView:
  - 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

gitmodel:
  An example that demonstrates how to implement a custom abstract item model.
treeview-dragdrop:
  An example that demonstrates drag and drop support in WTreeView.

### C) Changes that break backward compatibility

WApplication:
  `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.
JSignal:
  You can now pass the original (keyboard/mouse) JavaScript event as a parameter to custom signals.
WTreeView:
  access mouse event in itemClicked, doubleClicked and mouseWentDown signals.
WServer:
  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. Isntead, 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 stronly 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-releated 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 construtor 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-connnector 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.