coverity#1309261 Unchecked dynamic_cast

Change-Id: Idea3a9f3465387680b814dc53ed4c0b13265f9f6

svx/source/svdraw/sdrpaintwindow.cxx

@@ -201,9 +201,9 @@ void SdrPaintWindow::impCreateOverlayManager()
         // is it a window?
         if(OUTDEV_WINDOW == GetOutputDevice().GetOutDevType())
         {
-            vcl::Window* pWindow = dynamic_cast<vcl::Window*>(&GetOutputDevice());
+            vcl::Window& rWindow = dynamic_cast<vcl::Window&>(GetOutputDevice());
             // decide which OverlayManager to use
-            if(GetPaintView().IsBufferedOverlayAllowed() && mbUseBuffer && !pWindow->SupportsDoubleBuffering())
+            if(GetPaintView().IsBufferedOverlayAllowed() && mbUseBuffer && !rWindow.SupportsDoubleBuffering())
             {
                 // buffered OverlayManager, buffers its background and refreshes from there
                 // for pure overlay changes (no system redraw). The 3rd parameter specifies
@@ -226,8 +226,7 @@ void SdrPaintWindow::impCreateOverlayManager()
             // Request a repaint so that the buffered overlay manager fills
             // its buffer properly.  This is a workaround for missing buffer
             // updates.
-            if (pWindow != NULL)
-                pWindow->Invalidate();
+            rWindow.Invalidate();
 
             Color aColA(GetPaintView().getOptionsDrawinglayer().GetStripeColorA());
             Color aColB(GetPaintView().getOptionsDrawinglayer().GetStripeColorB());