Repaint widgets on screen change.

Add a screenChanged handler slot to QWidgetWindow,
which calls markDirty() on the backing store with
the BufferInvalid and UpdateNow flags set.

Update CocoaBackingStore to create a new buffer on
window devicePixelRatio change. Use the
QCocoaWindow::devicePixelRatio() implementation instead
of a duplicate implementation in the backing store.

The plan is to replace this implementation with one
based on QUpdateWindowRequestEvent for Qt 5.4

Change-Id: I8e521c53df4ac90815613e730fe821996334721f
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/widgets/kernel/qwidgetwindow_qpa_p.h b/src/widgets/kernel/qwidgetwindow_qpa_p.h
index 8d6f14a669..06ba8ea646 100644
--- a/src/widgets/kernel/qwidgetwindow_qpa_p.h
+++ b/src/widgets/kernel/qwidgetwindow_qpa_p.h
@@ -101,6 +101,7 @@ protected:
 
 private slots:
     void updateObjectName();
+    void repaintWindow();
 
 private:
     void updateGeometry();