Since I am using compiz on linux, the mail squeak window looks somewhat 
transparent or actually just mangled. It is not really transparent but the 
stuff behind it affects the way things are displayed. Often it helps to set 
the color depth to 32, but even that is difficult to do, because I can hardly 
read the menus.

I noticed the same phenomenon with qemu, but it was fixed in a recent version. 

Is there a way I can avoid this?

-- 
Martin