tdf#92055 - make ImplBorderWindow more tolerant of post-dispose events.

Change-Id: I9556c920e6fc8b5595eee6bd00d36669e1684e25
Reviewed-on: https://gerrit.libreoffice.org/16892Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>

vcl/source/window/brdwin.cxx

@@ -1851,26 +1851,31 @@ void ImplBorderWindow::dispose()
 
 void ImplBorderWindow::MouseMove( const MouseEvent& rMEvt )
 {
+    if (mpBorderView)
         mpBorderView->MouseMove( rMEvt );
 }
 
 void ImplBorderWindow::MouseButtonDown( const MouseEvent& rMEvt )
 {
+    if (mpBorderView)
         mpBorderView->MouseButtonDown( rMEvt );
 }
 
 void ImplBorderWindow::Tracking( const TrackingEvent& rTEvt )
 {
+    if (mpBorderView)
         mpBorderView->Tracking( rTEvt );
 }
 
 void ImplBorderWindow::Paint( vcl::RenderContext& rRenderContext, const Rectangle& )
 {
+    if (mpBorderView)
         mpBorderView->DrawWindow(rRenderContext, BORDERWINDOW_DRAW_ALL);
 }
 
 void ImplBorderWindow::Draw( const Rectangle&, OutputDevice* pOutDev, const Point& rPos )
 {
+    if (mpBorderView)
         mpBorderView->DrawWindow(*pOutDev, BORDERWINDOW_DRAW_ALL, &rPos);
 }