QWindowsBackingStore: Flush to correct window.

Task-number: QTBUG-25435

Change-Id: I13f57a328a7ac3402fe0def9d724f7e700016c80
Reviewed-by: Jonathan Liu <net147@gmail.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/plugins/platforms/windows/qwindowsbackingstore.cpp b/src/plugins/platforms/windows/qwindowsbackingstore.cpp
index 2cf9645786..fad7dbdbf4 100644
--- a/src/plugins/platforms/windows/qwindowsbackingstore.cpp
+++ b/src/plugins/platforms/windows/qwindowsbackingstore.cpp
@@ -78,11 +78,12 @@ QPaintDevice *QWindowsBackingStore::paintDevice()
 void QWindowsBackingStore::flush(QWindow *window, const QRegion &region,
                                         const QPoint &offset)
 {
+    Q_ASSERT(window);
     // TODO: Prepare paint for translucent windows.
     const QRect br = region.boundingRect();
     if (QWindowsContext::verboseBackingStore > 1)
         qDebug() << __FUNCTION__ << window << offset << br;
-    QWindowsWindow *rw = rasterWindow();
+    QWindowsWindow *rw = QWindowsWindow::baseWindowOf(window);
     const HDC dc = rw->getDC();
     if (!dc) {
         qErrnoWarning("%s: GetDC failed", __FUNCTION__);