Haven't found any other thread about this so I'm opening a new one.
When I open a menu I get graphical glitces, also metacity decorator is corrupted.
This issue appeared with Xorg 1.10 (from its first rc release),
it is reproducible with different graphic drivers (ati, nouveau, nvidia, gma500, vesa, vbox),
it is present with metacity and with metacity compositor, only with compiz activated is no more present.
this is a video with the problem: http://dl.dropbox.com/u/1338581/artefacts.ogv
and bug report: https://bugs.launchpad.net/xorg-server/+bug/726369