Qt 5.15.1 is a bug-fix release. It maintains both forward and backward
compatibility (source and binary) with Qt 5.15.0.

For more details, refer to the online documentation included in this
distribution. The documentation is also available online:

https://doc.qt.io/qt-5/index.html

The Qt version 5.15 series is binary compatible with the 5.14.x series.
Applications compiled for 5.14 will continue to run with 5.15.

Some of the changes listed in this file include issue tracking numbers
corresponding to tasks in the Qt Bug Tracker:

https://bugreports.qt.io/

Each of these identifiers can be entered in the bug tracker to obtain more
information about a particular change.

****************************************************************************
*                        Important Behavior Changes                        *
****************************************************************************

 - QSharedPointer objects will now call custom deleters even when the
   pointer being tracked was null. This behavior is the same as
   std::shared_ptr.
 - Restored pre-5.15.0 behavior when converting from QVariant* to QJson*
   types. Unforeseen consequences of changes in 5.15.0 caused QByteArray
   data to be base64url-encoded; the handling of QRegularExpression was
   also unintentionally changed. These conversions are now reverted to the
   prior behavior. Additionally fixed QJsonValue::fromVariant conversions
   for NaN and infinities: they should always convert to QJsonValue::Null.

****************************************************************************
*                                  QtCore                                  *
****************************************************************************

 - JSON
   * Fixed a regression from 5.14 that caused values of default-constructed
     QVariants in QVariantLists, QVariantMaps and QVariantHashes to
     disappear when converting to JSON via fromVariant{,List,Map,Hash}.

 - QCborMap
   * Fixed a bug that could cause the iterator returned from a failing key
     search with find() not to match end(). Now, every call to find() will
     detach in shared QCborMaps; to avoid this, use constFind() and
     constEnd().

 - QFile:
   * moveToTrash now creates the trash folder on Linux as
     $XDG_DATA_HOME/Trash, as required by the freedesktop.org spec.
   * moveToTrash supports relative file paths on Windows.

 - QImage:
   * Fixed buffer overflow in XBM parser.
   * [oss-fuzz-23988] Fixed buffer overflow in XPM parser.

 - QJsonDocument:
   * Fixed a bug that caused QJsonDocument's equality operator to crash if
     one of the operands was default-constructed and the other wasn't.

 - QString:
   * Fixed quadratic worst-case complexity of remove(QString). The function
     now has linear complexity in all cases.

 - QTimeLine:
   * Deprecated QTimeLine's curveShape property in favor of the easingCurve
     property.

 - QXmlStreamReader:
   * [oss-fuzz-24347] Reduced memory consumption when handling huge input data.

 - mkspecs:
   * Explicitly enable float-divide-by-zero when configuring Qt with
     "-sanitize undefined". Before clang 9, it was implicitly enabled when
     -fsanitize=undefined was set.

****************************************************************************
*                                  QtGui                                   *
****************************************************************************

 - QIcon:
   * [QTBUG-74252] If you call QIcon::setFallbackThemeName(), you should
     do it before the creation of the QGuiApplication; this now avoids
     a bug that resulted in the first loaded icons being empty.

 - HTML:
   * QTextDocument::toHtml() now exports letter and word spacing from the
     default format, if set, into the body tag. Such formatting can also
     be read back in.
   * [QTBUG-84981] Vertical alignment of images is now more compliant with
     the HTML standard: AlignBottom is the bottom of the line; AlignMiddle
     is between AlignTop and AlignBottom

 - Markdown:
   * [QTBUG-81306] QTextMarkdownImporter now correctly reads nested span
     formatting such as *italic ~~strikeout **bold `code` end**~~*
     including in link text and image alt text. The effects are mostly
     cumulative; however `code` blocks still completely override formatting.
   * [QTBUG-80603] QMarkdownWriter no longer tries to word-wrap code blocks;
     and code blocks nested in list items are formatted correctly.

 - Text:
   * Fixed a bug where glyphs would be clipped at very large sizes.

****************************************************************************
*                                QtTestLib                                 *
****************************************************************************

 - QCOMPARE:
   * QCOMPARE() now treats its values as equal when qFuzzyIsNull() is true
     for both of them.

****************************************************************************
*                                QtWidgets                                 *
****************************************************************************

 - QApplication:
   * Wheel events from a device that creates an event stream are correctly
     delivered to the widget that accepts the first wheel event in the
     stream.

 - QListView:
   * Moving selected items within a list view by drag'n'drop will maintain
     the selection of those items.

 - QMenu:
   * [QTBUG-84926] Fixed a regression that prevented pressing the mouse
     to open a menu, dragging over a menu item, and releasing to select it.
   * [QTBUG-76162] A submenu is always shown on its parent menu's screen.
     A text control's context menu is now always shown on the same screen.
     A menu on a QMenuBar can only be shown on the screen(s) where the
     menubar is visible.

 - QWidget:
   * setFocusProxy no longer moves focus away from a previously set focus
     proxy, restoring pre-Qt 5.13.1 behavior.

****************************************************************************
*                        Platform-specific changes                         *
****************************************************************************

 - Android
   * [QTBUG-83089] Support setting mimetypes and and namefilters for Android
     native file dialog.

 - iOS
   * [QTBUG-83811] When text is selected using handles in a read-only
     control, it's now possible for the edit menu popover to be configured
     to have a Copy action instead of Paste. So far this is used in QtPDF.

 - Linux
   * QFileDialog will open directories through the portal if required
     version of xdg-desktop-portal is running on the system.

 - X11
   * [QTBUG-83446] Fixed a drag-and-drop crash due to an invalid reply in
     QXcbDrag.
   * [QTBUG-56218] When keyboard modifiers change during drag-and-drop,
     a QDragMoveEvent is sent even if the mouse doesn't actually move, to
     allow updating the drop action and cursor.
   * [QTBUG-85275] Window geometry coordinates are now allowed to be up to
     32767.
   * [QTBUG-25351] The new QT_QPA_SYSTEM_ICON_THEME variable can override
     the icon theme name.

****************************************************************************
*                             Third-Party Code                             *
****************************************************************************

 - sqlite:
   * Upgraded to v3.32.1
   * Upgraded to v3.32.3
 - PCRE2 was updated to version 10.35.
 - libjpeg-turbo was updated to version 2.0.5
 - Documented the use of Khronos headers under MIT license in Qt GUI
   (ANGLE).