Windows: Fix setting of layered windows.

The setting/clearing of WS_EX_LAYERED in the backing store
interfered with the setting/clearing in setWindowOpacity
when combining translucent and non-opaque windows.
Introduce QWindowsWindow::setWindowLayered to handle
it consistently.

Task-number: QTBUG-29010
Task-number: QTBUG-28531
Change-Id: Ib6e2740aae417bdf7b3db9ef7deb646be98df1d6
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

1 files changed, 1 insertions, 5 deletions

diff --git a/src/plugins/platforms/windows/qwindowsbackingstore.cpp b/src/plugins/platforms/windows/qwindowsbackingstore.cpp
index 792eaf0fdc..0a7ff61b7b 100644
--- a/src/plugins/platforms/windows/qwindowsbackingstore.cpp
+++ b/src/plugins/platforms/windows/qwindowsbackingstore.cpp
@@ -88,11 +88,7 @@ void QWindowsBackingStore::flush(QWindow *window, const QRegion &region,
     QWindowsWindow *rw = QWindowsWindow::baseWindowOf(window);
 
 #ifndef Q_OS_WINCE
-    if (rw->format().hasAlpha() && (window->flags() & Qt::FramelessWindowHint)) {
-        const long wl = GetWindowLong(rw->handle(), GWL_EXSTYLE);
-        if ((wl & WS_EX_LAYERED) == 0)
-            SetWindowLong(rw->handle(), GWL_EXSTYLE, wl | WS_EX_LAYERED);
-
+    if (QWindowsWindow::setWindowLayered(rw->handle(), window->flags(), rw->format().hasAlpha(), rw->opacity())) {
         QRect r = window->frameGeometry();
         QPoint frameOffset(window->frameMargins().left(), window->frameMargins().top());
         QRect dirtyRect = br.translated(offset + frameOffset);