http://bugs.winehq.org/show_bug.cgi?id=12060
--- Comment #4 from Roderick Colenbrander thunderbird2k@gmx.net 2008-03-20 10:28:08 --- Let me guess you are using either DRI drivers (intel, ati ..) or ATI's drivers? If so these drivers don't have proper GLX + XComposite support yet which causes this issue. If this is indeed the case then the issue is a driver bug and not a Wine one. Nvidia should work fine BTW.