Qt 4.6 introduces many new features and improvements as well as bugfixes

over the 4.5.x series. For more details, refer to the online documentation

included in this distribution. The documentation is also available online:

  http://qt.nokia.com/doc/4.6

The Qt version 4.6 series is binary compatible with the 4.5.x series.

Applications compiled for 4.5 will continue to run with 4.6.

Some of the changes listed in this file include issue tracking numbers

corresponding to tasks in the Task Tracker:

  http://qt.nokia.com/developer/task-tracker

Each of these identifiers can be entered in the task tracker to obtain more

information about a particular change.

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*                           General                                        *

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 - QtDBus

   * The minimum required version of the D-Bus reference library is

     now 0.93.

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*                          Library                                         *

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    * [245219] Added QXmlQuery::setFocus(const QString &focus);

 - QVariant

    * Many optimisations

    * Added QVariant::toFloat() and QVariant::toReal()

    * Added QVariant(float) constructor

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*                      Platform Specific Changes                           *

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 - Significant external contribution from Milan Burda for planned removal

   of (non-unicode) Windows 9x/ME support.

 - QRegion is no longer a GDI object by default. This means it is no

   longer subject to gui-thread only nor does it potentially impact

   the 10.000 GDI object limit per process. By explicitly calling

   .handle() a GDI object will be created and memory managed by

   QRegion. The native handle is for reading out only. Any GDI calls

   made on the HRGN handle will not affect the QRegion.

 - [259221] QFileInfo::symLinkTarget() now supports NTFS symbolic links

   thanks to Konstantin Ritt (merge request 1217).

 - The reading code of QLocalSocket on Windows has been rewritten to improve

   reading performance.

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* Important Behavior Changes *

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 - The experimental Direct3D paint engine has been removed. The reason for

   this is that Nokia focuses on OpenGL for desktop hardware accelerated

   rendering.

 - The default engine used to draw onto OpenGL buffers has changed in

   Qt 4.6. The QPaintEngine::OpenGL2 engine is now used as the default

   engine. This *may* cause compatibility problems for applications

   that use a mix of QPainter and native OpenGL calls to draw into a GL

   buffer. Use the QGL::setPreferredPaintEngine() function to enforce

   usage of the old GL paint engine.

 - When mixing OpenGL and QPainter calls you need to surround your

   custom OpenGL calls with QPainter::beginNativePainting() and

   QPainter::endNativePainting().

   This is to ensure that the paint engine flushes any pending drawing and sets

   up the GL modelview/projection matrices properly before you can issue custom

   OpenGL calls, and to let the paint engine synchronize to the painter state

   before resuming regular QPainter based drawing.

 - Graphics View has undergone heavy optimization work, and as a result of

   this work, the following behavior changes were introduced.

   a) QStyleOptionGraphicsItem::exposedRect now contains the item's bounding

      rectangle, and QStyleOptionGraphicsItem::matrix is uninitialized by

      default. You can enable an exact exposed rectangle and a correct matrix

      by enabling the flag QGraphicsItem::ItemUsesExtendedStyleOptions.

   b) QStyleOptionGraphicsItem::levelOfDetails is obsoleted and its value is

      always initialized to 1. Instead you can call

      QStyleOptionGraphicsItem::levelOfDetailFromTransform(const QTransform &)

      to determine the level of detail.

   c) QGraphicsView no longer calls QGraphicsView::drawItems(), and in turn

      QGraphicsScene::drawItems(), by default. You can get the old behavior

      back by enabling QGraphicsView::IndirectPainting.

   d) QGraphicsItem no longer calls itemChange() for position and

      transformation changes. If you want to receive notifications for changes

      to the item's position and transformation, you can set the flag

      QGraphicsItem::ItemSendsGeometryChanges (which is enabled by default by

      QGraphicsWidget and QGraphicsProxyWidget).

 - QDesktopWidget on X11 no longer emits the resized(int) signal when screens

   are added or removed. This was not done on other platforms. Use the

   screenCountChanged signal instead

 - QUrl's parser is more strict when for hostnames in URLs. QUrl now

   enforces STD 3 rules:

    * each individual hostname section (between dots) must be at most

      63 ASCII characters in length;

    * only letters, digits, and the hyphen character are allowed in the

      ASCII range; letters outside the ASCII range follow the normal

      IDN rules

   That means QUrl no longer accepts some URLs that were invalid

   before, but weren't interpreted as such.

 - The Unix configure-time check for STL is stricter now in Qt

   4.6.0. This means some legacy STL implementations may fail to pass

   the test and, therefore, Qt will automatically disable STL support.

   This is a binary-compatible change: existing code will continue to

   work without being recompiled. However, it affects the source code,

   since some STL-compatibility API will not be enabled.

   Platforms affected by this change:

     * solaris-cc-* with the default (Cstd) C++ STL library

       recommendation: use -library=stlport4

       See Sun Studio's documentation for the effects of this option

 - QVariant has now a new implicit constructor that takes a float. This

   means that code that assigned a float to a variant would create a

   variant with userType QMetaType::Float, instead of QVariant::Double.

 - QDataStream will now read and write all floating point numbers with the 

   same precision, regardless of whether it's streamed into or out from a 

   float or double. This is to maintain compatibility across platforms with

   a different default precision for qreal. The default is 64-bit precision

   for all floating point numbers, and this can be changed using the new 

   function setFloatingPointPrecision(). Set Qt_4_5 as the version of the 

   QDataStream to get the behavior of previous versions.