Comment 6 for bug 425823

From my recent testing with the nv-driver and metacity+compositor this seems to be a metacity-specfic issue. Bubbles are rendered by notify-osd, but metacity does not update the screen immediately. For example if a bubble does not show up as expected moving a window around in the area where the bubble should show up, causes metacity to update that part of the screen exposing the bubble. I expect this to be some XDamage/XFixes issue in metacity's code. There's nothing which could be done from within notify-osd to work around this case.