Merge branch '4.5' of git@scm.dev.troll.no:qt/qt

7 files changed, 180 insertions, 176 deletions

diff --git a/src/gui/dialogs/qfiledialog.cpp b/src/gui/dialogs/qfiledialog.cpp
index d786f3e..073c25b 100644
--- a/src/gui/dialogs/qfiledialog.cpp
+++ b/src/gui/dialogs/qfiledialog.cpp
@@ -1538,52 +1538,51 @@ extern QString qt_win_get_existing_directory(const QFileDialogArgs &args);
 #endif
 
 /*!
-  This is a convenience static function that returns an existing file
-  selected by the user. If the user presses Cancel, it returns a null
-  string.
+    This is a convenience static function that returns an existing file
+    selected by the user. If the user presses Cancel, it returns a null string.
 
-  \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 8
+    \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 8
 
-  The function creates a modal file dialog with the given \a parent widget.
-  If the parent is not 0, the dialog will be shown centered over the
-  parent widget.
+    The function creates a modal file dialog with the given \a parent widget.
+    If \a parent is not 0, the dialog will be shown centered over the parent
+    widget.
 
-  The file dialog's working directory will be set to \a dir.  If \a
-  dir includes a file name, the file will be selected. Only files
-  that match the given \a filter are shown. The filter selected is
-  set to \a selectedFilter. The parameters \a dir, \a
-  selectedFilter, and \a filter may be empty strings. If you want
-  multiple filters, separate them with ';;', for example:
+    The file dialog's working directory will be set to \a dir. If \a dir
+    includes a file name, the file will be selected. Only files that match the
+    given \a filter are shown. The filter selected is set to \a selectedFilter.
+    The parameters \a dir, \a selectedFilter, and \a filter may be empty
+    strings. If you want multiple filters, separate them with ';;', for
+    example:
 
-  \code
+    \code
     "Images (*.png *.xpm *.jpg);;Text files (*.txt);;XML files (*.xml)"
-  \endcode
+    \endcode
 
-  The \a options argument holds various
-  options about how to run the dialog, see the QFileDialog::Option enum for
-  more information on the flags you can pass.
+    The \a options argument holds various options about how to run the dialog,
+    see the QFileDialog::Option enum for more information on the flags you can
+    pass.
 
-  The dialog's caption is set to \a caption. If \a caption is not
-  specified then a default caption will be used.
+    The dialog's caption is set to \a caption. If \a caption is not specified
+    then a default caption will be used.
 
-  Under Windows and Mac OS X, this static function will use the native
-  file dialog and not a QFileDialog.
+    On Windows and Mac OS X, this static function will use the native file
+    dialog and not a QFileDialog.
 
-  Note that on Windows the dialog will spin a blocking modal event loop
-  that will not dispatch any QTimers, and if parent is not 0 then it will
-  position the dialog just under the parent's title bar.
+    On Windows the dialog will spin a blocking modal event loop that will not
+    dispatch any QTimers, and if \a parent is not 0 then it will position the
+    dialog just below the parent's title bar.
 
-  Under Unix/X11, the normal behavior of the file dialog is to resolve
-  and follow symlinks. For example, if \c{/usr/tmp} is a symlink to
-  \c{/var/tmp}, the file dialog will change to \c{/var/tmp} after
-  entering \c{/usr/tmp}. If \a options includes DontResolveSymlinks,
-  the file dialog will treat symlinks as regular directories.
+    On Unix/X11, the normal behavior of the file dialog is to resolve and
+    follow symlinks. For example, if \c{/usr/tmp} is a symlink to \c{/var/tmp},
+    the file dialog will change to \c{/var/tmp} after entering \c{/usr/tmp}. If
+    \a options includes DontResolveSymlinks, the file dialog will treat
+    symlinks as regular directories.
 
-  \warning Do not delete \a parent during the execution of the dialog.
-           If you want to do this, you should create the dialog
-           yourself using one of the QFileDialog constructors.
+    \warning Do not delete \a parent during the execution of the dialog. If you
+    want to do this, you should create the dialog yourself using one of the
+    QFileDialog constructors.
 
-  \sa getOpenFileNames(), getSaveFileName(), getExistingDirectory()
+    \sa getOpenFileNames(), getSaveFileName(), getExistingDirectory()
 */
 QString QFileDialog::getOpenFileName(QWidget *parent,
                                const QString &caption,
@@ -1626,54 +1625,53 @@ QString QFileDialog::getOpenFileName(QWidget *parent,
 }
 
 /*!
-  This is a convenience static function that will return one or more
-  existing files selected by the user.
+    This is a convenience static function that will return one or more existing
+    files selected by the user.
 
-  \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 9
+    \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 9
 
-  This function creates a modal file dialog with the given \a parent
-  widget. If the parent is not 0, the dialog will be shown centered
-  over the parent widget.
+    This function creates a modal file dialog with the given \a parent widget.
+    If \a parent is not 0, the dialog will be shown centered over the parent
+    widget.
 
-  The file dialog's working directory will be set to \a dir. If \a
-  dir includes a file name, the file will be selected. The filter
-  is set to \a filter so that only those files which match the filter
-  are shown. The filter selected is set to \a selectedFilter. The parameters
-  \a dir, \a selectedFilter and \a filter may be empty strings. If you
-  need multiple filters, separate them with ';;', for instance:
+    The file dialog's working directory will be set to \a dir. If \a dir
+    includes a file name, the file will be selected. The filter is set to
+    \a filter so that only those files which match the filter are shown. The
+    filter selected is set to \a selectedFilter. The parameters \a dir,
+    \a selectedFilter and \a filter may be empty strings. If you need multiple
+    filters, separate them with ';;', for instance:
 
-  \code
+    \code
     "Images (*.png *.xpm *.jpg);;Text files (*.txt);;XML files (*.xml)"
-  \endcode
+    \endcode
 
-  The dialog's caption is set to \a caption. If \a caption is not
-  specified then a default caption will be used.
+    The dialog's caption is set to \a caption. If \a caption is not specified
+    then a default caption will be used.
 
-  Under Windows and Mac OS X, this static function will use the native
-  file dialog and not a QFileDialog. On Mac OS X, the \a dir argument
-  is ignored, the native dialog always displays the last visited directory.
+    On Windows and Mac OS X, this static function will use the native file
+    dialog and not a QFileDialog.
 
-  Note that on Windows the dialog will spin a blocking modal event loop
-  that will not dispatch any QTimers, and if parent is not 0 then it will
-  position the dialog just under the parent's title bar.
+    On Windows the dialog will spin a blocking modal event loop that will not
+    dispatch any QTimers, and if \a parent is not 0 then it will position the
+    dialog just below the parent's title bar.
 
-  Under Unix/X11, the normal behavior of the file dialog is to resolve
-  and follow symlinks. For example, if \c{/usr/tmp} is a symlink to
-  \c{/var/tmp}, the file dialog will change to \c{/var/tmp} after
-  entering \c{/usr/tmp}. The \a options argument holds various
-  options about how to run the dialog, see the QFileDialog::Option enum for
-  more information on the flags you can pass.
+    On Unix/X11, the normal behavior of the file dialog is to resolve and
+    follow symlinks. For example, if \c{/usr/tmp} is a symlink to \c{/var/tmp},
+    the file dialog will change to \c{/var/tmp} after entering \c{/usr/tmp}.
+    The \a options argument holds various options about how to run the dialog,
+    see the QFileDialog::Option enum for more information on the flags you can
+    pass.
 
-  Note that if you want to iterate over the list of files, you should
-  iterate over a copy. For example:
+    \note If you want to iterate over the list of files, you should iterate
+    over a copy. For example:
 
     \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 10
 
-  \warning Do not delete \a parent during the execution of the dialog.
-           If you want to do this, you should create the dialog
-           yourself using one of the QFileDialog constructors.
+    \warning Do not delete \a parent during the execution of the dialog. If you
+    want to do this, you should create the dialog yourself using one of the
+    QFileDialog constructors.
 
-  \sa getOpenFileName(), getSaveFileName(), getExistingDirectory()
+    \sa getOpenFileName(), getSaveFileName(), getExistingDirectory()
 */
 QStringList QFileDialog::getOpenFileNames(QWidget *parent,
                                           const QString &caption,
@@ -1717,54 +1715,54 @@ QStringList QFileDialog::getOpenFileNames(QWidget *parent,
 }
 
 /*!
-  This is a convenience static function that will return a file name
-  selected by the user. The file does not have to exist.
+    This is a convenience static function that will return a file name selected
+    by the user. The file does not have to exist.
 
-  It creates a modal file dialog with the given \a parent widget. If the
-  parent is not 0, the dialog will be shown centered over the parent
-  widget.
+    It creates a modal file dialog with the given \a parent widget. If
+    \a parent is not 0, the dialog will be shown centered over the parent
+    widget.
 
-  \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 11
+    \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 11
 
-  The file dialog's working directory will be set to \a dir. If \a
-  dir includes a file name, the file will be selected. Only files that
-  match the \a filter are shown. The filter selected is set to
-  \a selectedFilter. The parameters \a dir, \a selectedFilter, and
-  \a filter may be empty strings. Multiple filters are separated with ';;'.
-  For instance:
+    The file dialog's working directory will be set to \a dir. If \a dir
+    includes a file name, the file will be selected. Only files that match the
+    \a filter are shown. The filter selected is set to \a selectedFilter. The
+    parameters \a dir, \a selectedFilter, and \a filter may be empty strings.
+    Multiple filters are separated with ';;'. For instance:
 
-  \code
+    \code
     "Images (*.png *.xpm *.jpg);;Text files (*.txt);;XML files (*.xml)"
-  \endcode
+    \endcode
 
-  The \a options argument holds various
-  options about how to run the dialog, see the QFileDialog::Option enum for
-  more information on the flags you can pass.
+    The \a options argument holds various options about how to run the dialog,
+    see the QFileDialog::Option enum for more information on the flags you can
+    pass.
 
-  The default filter can be chosen by setting \a selectedFilter to the desired value.
+    The default filter can be chosen by setting \a selectedFilter to the
+    desired value.
 
-  The dialog's caption is set to \a caption. If \a caption is not
-  specified then a default caption will be used.
+    The dialog's caption is set to \a caption. If \a caption is not specified,
+    a default caption will be used.
 
-  Under Windows and Mac OS X, this static function will use the native
-  file dialog and not a QFileDialog.
+    On Windows and Mac OS X, this static function will use the native file
+    dialog and not a QFileDialog.
 
-  Note that on Windows the dialog will spin a blocking modal event loop
-  that will not dispatch any QTimers, and if parent is not 0 then it will
-  position the dialog just under the parent's title bar.
-  On Mac OS X, the filter argument is ignored.
+    On Windows the dialog will spin a blocking modal event loop that will not
+    dispatch any QTimers, and if \a parent is not 0 then it will position the
+    dialog just below the parent's title bar. On Mac OS X, with its native file
+    dialog, the filter argument is ignored.
 
-  Under Unix/X11, the normal behavior of the file dialog is to resolve
-  and follow symlinks. For example, if \c{/usr/tmp} is a symlink to
-  \c{/var/tmp}, the file dialog will change to \c{/var/tmp} after
-  entering \c{/usr/tmp}. If \a options includes DontResolveSymlinks,
-  the file dialog will treat symlinks as regular directories.
+    On Unix/X11, the normal behavior of the file dialog is to resolve and
+    follow symlinks. For example, if \c{/usr/tmp} is a symlink to \c{/var/tmp},
+    the file dialog will change to \c{/var/tmp} after entering \c{/usr/tmp}. If
+    \a options includes DontResolveSymlinks the file dialog will treat symlinks
+    as regular directories.
 
-  \warning Do not delete \a parent during the execution of the dialog.
-           If you want to do this, you should create the dialog
-           yourself using one of the QFileDialog constructors.
+    \warning Do not delete \a parent during the execution of the dialog. If you
+    want to do this, you should create the dialog yourself using one of the
+    QFileDialog constructors.
 
-  \sa getOpenFileName(), getOpenFileNames(), getExistingDirectory()
+    \sa getOpenFileName(), getOpenFileNames(), getExistingDirectory()
 */
 QString QFileDialog::getSaveFileName(QWidget *parent,
                                      const QString &caption,
@@ -1810,46 +1808,43 @@ QString QFileDialog::getSaveFileName(QWidget *parent,
 }
 
 /*!
-  This is a convenience static function that will return an existing
-  directory selected by the user.
+    This is a convenience static function that will return an existing
+    directory selected by the user.
 
-  \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 12
+    \snippet doc/src/snippets/code/src_gui_dialogs_qfiledialog.cpp 12
 
-  This function creates a modal file dialog with the given \a parent
-  widget. If the parent is not 0, the dialog will be shown centered over
-  the parent widget.
+    This function creates a modal file dialog with the given \a parent widget.
+    If \a parent is not 0, the dialog will be shown centered over the parent
+    widget.
 
-  The dialog's working directory is set to \a dir, and the caption is
-  set to \a caption. Either of these may be an empty string in which case
-  the current directory and a default caption will be used
-  respectively.
+    The dialog's working directory is set to \a dir, and the caption is set to
+    \a caption. Either of these may be an empty string in which case the
+    current directory and a default caption will be used respectively.
 
-  The \a options argument holds various
-  options about how to run the dialog, see the QFileDialog::Option enum for
-  more information on the flags you can pass. Note that \l{QFileDialog::}{ShowDirsOnly}
-  must be set to ensure a native file dialog.
+    The \a options argument holds various options about how to run the dialog,
+    see the QFileDialog::Option enum for more information on the flags you can
+    pass. To ensure a native file dialog, \l{QFileDialog::}{ShowDirsOnly} must
+    be set.
 
-  Under Windows and Mac OS X, this static function will use the native
-  file dialog and not a QFileDialog. On Mac OS X, the \a dir argument
-  is ignored, the native dialog always displays the last visited directory.
-  On Windows CE, if the device has no native file dialog, a QFileDialog
-  will be used.
+    On Windows and Mac OS X, this static function will use the native file
+    dialog and not a QFileDialog. On Windows CE, if the device has no native
+    file dialog, a QFileDialog will be used.
 
-  Under Unix/X11, the normal behavior of the file dialog is to resolve
-  and follow symlinks. For example, if \c{/usr/tmp} is a symlink to
-  \c{/var/tmp}, the file dialog will change to \c{/var/tmp} after
-  entering \c{/usr/tmp}. If \a options includes DontResolveSymlinks,
-  the file dialog will treat symlinks as regular directories.
+    On Unix/X11, the normal behavior of the file dialog is to resolve and
+    follow symlinks. For example, if \c{/usr/tmp} is a symlink to \c{/var/tmp},
+    the file dialog will change to \c{/var/tmp} after entering \c{/usr/tmp}. If
+    \a options includes DontResolveSymlinks, the file dialog will treat
+    symlinks as regular directories.
 
-  Note that on Windows the dialog will spin a blocking modal event loop
-  that will not dispatch any QTimers, and if parent is not 0 then it will
-  position the dialog just under the parent's title bar.
+    On Windows the dialog will spin a blocking modal event loop that will not
+    dispatch any QTimers, and if \a parent is not 0 then it will position the
+    dialog just below the parent's title bar.
 
-  \warning Do not delete \a parent during the execution of the dialog.
-           If you want to do this, you should create the dialog
-           yourself using one of the QFileDialog constructors.
+    \warning Do not delete \a parent during the execution of the dialog. If you
+    want to do this, you should create the dialog yourself using one of the
+    QFileDialog constructors.
 
-  \sa getOpenFileName(), getOpenFileNames(), getSaveFileName()
+    \sa getOpenFileName(), getOpenFileNames(), getSaveFileName()
 */
 QString QFileDialog::getExistingDirectory(QWidget *parent,
                                           const QString &caption,
diff --git a/src/gui/dialogs/qfontdialog_mac.mm b/src/gui/dialogs/qfontdialog_mac.mm
index 42be3be..50917a1 100644
--- a/src/gui/dialogs/qfontdialog_mac.mm
+++ b/src/gui/dialogs/qfontdialog_mac.mm
@@ -87,7 +87,6 @@ const int StyleMask = NSTitledWindowMask | NSClosableWindowMask | NSResizableWin
     NSButton *mOkButton;
     NSButton *mCancelButton;
     QFontDialogPrivate *mPriv;
-    NSFont *mCocoaFont;
     QFont *mQtFont;
     BOOL mPanelHackedWithButtons;
     CGFloat mDialogExtraWidth;
@@ -119,6 +118,29 @@ const int StyleMask = NSTitledWindowMask | NSClosableWindowMask | NSResizableWin
 - (void)cleanUpAfterMyself;
 @end
 
+static QFont qfontForCocoaFont(NSFont *cocoaFont, const QFont &resolveFont)
+{
+    QFont newFont;
+    if (cocoaFont) {
+        int pSize = qRound([cocoaFont pointSize]);
+        QString family(QCFString::toQString(reinterpret_cast<CFStringRef>([cocoaFont familyName])));
+        QString typeface(QCFString::toQString(reinterpret_cast<CFStringRef>([cocoaFont fontName])));
+//        qDebug() << "original family" << family << "typeface" << typeface << "psize" << pSize;
+        int hyphenPos = typeface.indexOf(QLatin1Char('-'));
+        if (hyphenPos != -1) {
+            typeface.remove(0, hyphenPos + 1);
+        } else {
+            typeface = QLatin1String("Normal");
+        }
+//        qDebug() << " massaged family" << family << "typeface" << typeface << "psize" << pSize;
+        newFont = QFontDatabase().font(family, typeface, pSize);
+        newFont.setUnderline(resolveFont.underline());
+        newFont.setStrikeOut(resolveFont.strikeOut());
+
+    }
+    return newFont;
+}
+
 @implementation QCocoaFontPanelDelegate
 - (id)initWithFontPanel:(NSFontPanel *)panel
        stolenContentView:(NSView *)stolenContentView
@@ -134,7 +156,6 @@ const int StyleMask = NSTitledWindowMask | NSClosableWindowMask | NSResizableWin
     mOkButton = okButton;
     mCancelButton = cancelButton;
     mPriv = priv;
-    mCocoaFont = 0;
     mPanelHackedWithButtons = (okButton != 0);
     mDialogExtraWidth = extraWidth;
     mDialogExtraHeight = extraHeight;
@@ -155,42 +176,14 @@ const int StyleMask = NSTitledWindowMask | NSClosableWindowMask | NSResizableWin
 
 - (void)dealloc
 {
-    if (mCocoaFont)
-        [mCocoaFont release];
     delete mQtFont;
     [super dealloc];
 }
 
 - (void)changeFont:(id)sender
 {
-    Q_UNUSED(sender);
-
-    QFont newFont;
-
-    if (mCocoaFont)
-        [mCocoaFont autorelease];
     NSFont *dummyFont = [NSFont userFontOfSize:12.0];
-    mCocoaFont = [sender convertFont:dummyFont];
-    if (mCocoaFont) {
-        [mCocoaFont retain];
-
-        int pSize = qRound([mCocoaFont pointSize]);
-        QString family(QCFString::toQString(reinterpret_cast<CFStringRef>([mCocoaFont familyName])));
-        QString typeface(QCFString::toQString(reinterpret_cast<CFStringRef>([mCocoaFont fontName])));
-//        qDebug() << "original family" << family << "typeface" << typeface << "psize" << pSize;
-        int hyphenPos = typeface.indexOf(QLatin1Char('-'));
-        if (hyphenPos != -1) {
-            typeface.remove(0, hyphenPos + 1);
-        } else {
-            typeface = QLatin1String("Normal");
-        }
-//        qDebug() << " massaged family" << family << "typeface" << typeface << "psize" << pSize;
-        newFont = QFontDatabase().font(family, typeface, pSize);
-        newFont.setUnderline(mQtFont->underline());
-        newFont.setStrikeOut(mQtFont->strikeOut());
-    }
-
-    [self setQtFont:newFont];
+    [self setQtFont:qfontForCocoaFont([sender convertFont:dummyFont], *mQtFont)];
     if (mPriv)
         mPriv->updateSampleFont(*mQtFont);
 }
@@ -317,6 +310,9 @@ const int StyleMask = NSTitledWindowMask | NSClosableWindowMask | NSResizableWin
 - (void)onOkClicked
 {
     Q_ASSERT(mPanelHackedWithButtons);
+    NSFontManager *fontManager = [NSFontManager sharedFontManager];
+    [self setQtFont:qfontForCocoaFont([fontManager convertFont:[fontManager selectedFont]],
+                                      *mQtFont)];
     [[mStolenContentView window] close];
     [self finishOffWithCode:NSOKButton];
 }
@@ -374,16 +370,7 @@ const int StyleMask = NSTitledWindowMask | NSClosableWindowMask | NSResizableWin
             mModalSession = 0;
         }
 
-        // temporary hack to work around bug in deleteLater() in Qt/Mac Cocoa
-#if 1
-        bool deleteDialog = mPriv->fontDialog()->testAttribute(Qt::WA_DeleteOnClose);
-        mPriv->fontDialog()->setAttribute(Qt::WA_DeleteOnClose, false);
-#endif
         mPriv->done((code == NSOKButton) ? QDialog::Accepted : QDialog::Rejected);
-#if 1
-        if (deleteDialog)
-            delete mPriv->fontDialog();
-#endif
     } else {
         [NSApp stopModalWithCode:code];
     }
diff --git a/src/gui/image/qpixmapcache.cpp b/src/gui/image/qpixmapcache.cpp
index eedb6a3..458d6b9 100644
--- a/src/gui/image/qpixmapcache.cpp
+++ b/src/gui/image/qpixmapcache.cpp
@@ -187,6 +187,11 @@ bool QPMCache::insert(const QString& key, const QPixmap &pixmap, int cost)
         cacheKeys.insert(key, cacheKey);
         return true;
     }
+    qint64 oldCacheKey = cacheKeys.value(key, -1);
+    //If for the same key we add already a pixmap we should delete it
+    if (oldCacheKey != -1)
+        QCache<qint64, QDetachedPixmap>::remove(oldCacheKey);
+
     bool success = QCache<qint64, QDetachedPixmap>::insert(cacheKey, new QDetachedPixmap(pixmap), cost);
     if (success) {
         cacheKeys.insert(key, cacheKey);
diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 1635912..9f0d2a4 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -183,6 +183,7 @@ QWidgetPrivate::QWidgetPrivate(int version) :
         ,inDirtyList(0)
         ,isScrolled(0)
         ,isMoved(0)
+        ,usesDoubleBufferedGLContext(0)
 #ifdef Q_WS_WIN
         ,noPaintOnScreen(0)
 #endif
@@ -2132,6 +2133,10 @@ QWidget *QWidget::find(WId id)
     If a widget is non-native (alien) and winId() is invoked on it, that widget
     will be provided a native handle.
 
+    On Mac OS X, the type returned depends on which framework Qt was linked
+    against. If Qt is using Carbon, the {WId} is actually an HIViewRef. If Qt
+    is using Cocoa, {WId} is a pointer to an NSView.
+
     \note We recommend that you do not store this value as it is likely to
     change at run-time.
 
diff --git a/src/gui/kernel/qwidget_p.h b/src/gui/kernel/qwidget_p.h
index c403ccc..8731551 100644
--- a/src/gui/kernel/qwidget_p.h
+++ b/src/gui/kernel/qwidget_p.h
@@ -531,6 +531,7 @@ public:
     uint inDirtyList : 1;
     uint isScrolled : 1;
     uint isMoved : 1;
+    uint usesDoubleBufferedGLContext : 1;
 
 #ifdef Q_WS_WIN
     uint noPaintOnScreen : 1; // see qwidget_win.cpp ::paintEngine()
diff --git a/src/gui/painting/qbackingstore.cpp b/src/gui/painting/qbackingstore.cpp
index fbac811a..34df6c9 100644
--- a/src/gui/painting/qbackingstore.cpp
+++ b/src/gui/painting/qbackingstore.cpp
@@ -1517,13 +1517,20 @@ void QWidgetPrivate::repaint_sys(const QRegion &rgn)
         extra->staticContentsSize = data.crect.size();
     }
 
+    QPaintEngine *engine = q->paintEngine();
+    // QGLWidget does not support partial updates if:
+    // 1) The context is double buffered
+    // 2) The context is single buffered and auto-fill background is enabled.
+    const bool noPartialUpdateSupport = (engine && engine->type() == QPaintEngine::OpenGL)
+                                        && (usesDoubleBufferedGLContext || q->autoFillBackground());
+    QRegion toBePainted(noPartialUpdateSupport ? q->rect() : rgn);
+
 #ifdef Q_WS_MAC
     // No difference between update() and repaint() on the Mac.
-    update_sys(rgn);
+    update_sys(toBePainted);
     return;
 #endif
 
-    QRegion toBePainted(rgn);
     toBePainted &= clipRect();
     clipToEffectiveMask(toBePainted);
     if (toBePainted.isEmpty())
diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index b8fa133..18d9125 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -2452,6 +2452,10 @@ bool QGLContext::create(const QGLContext* shareContext)
         return false;
     reset();
     d->valid = chooseContext(shareContext);
+    if (d->valid && d->paintDevice->devType() == QInternal::Widget) {
+        QWidgetPrivate *wd = qt_widget_private(static_cast<QWidget *>(d->paintDevice));
+        wd->usesDoubleBufferedGLContext = d->glFormat.doubleBuffer();
+    }
     if (d->sharing)  // ok, we managed to share
         qgl_share_reg()->addShare(this, shareContext);
     return d->valid;