Respect image mask in the docview sample.

Draw images with transparency, if any.

See #13881.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70406 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/docview/view.cpp

@@ -336,7 +336,7 @@ void ImageView::OnDraw(wxDC* dc)
     wxImage image = GetDocument()->GetImage();
     if ( image.IsOk() )
     {
-        dc->DrawBitmap(wxBitmap(image), 0, 0);
+        dc->DrawBitmap(wxBitmap(image), 0, 0, true /* use mask */);
     }
 }