Comment 2 for bug 462647

No, I'm not using a compositing window manager.

The point is, even if the bubble disappear, people (at least all those I talked to) don't get that the bubble is not "going away", it is just "moving" to give you access to the underlying window. An short animation that show the notification moving away (maybe moving right outside the screen) would instantly suggest that it is only momentarily moving away.

See also the related bug #371093.