If
- window A is above window B, and
- window A has been moved,
then window B receives a redraw event.
But if that move was 1px right or down, window B didn't receive an event
because of off-by-one error. Now it's fixed.
git-svn-id: svn://kolibrios.org@9221 a494cfbc-eb01-0410-851d-a64ba20cac60