Am 11.09.2008 um 15:39 schrieb Juan Vuletich:

> Usually the VM / OS ignores the alpha channel of the display. But  
> with composite window managers on Linux, it is honored, and the bug  
> is exposed.


This is a VM problem and has a fix, as already discussed previously:

http://lists.squeakfoundation.org/pipermail/squeak-dev/2008-August/130935.html

- Bert -