X11 apparently got a bit worse again, whole windows do not redraw
correctly but get random content and need to be minimized/reopened to
get a refresh, when covered damaged sections contain garbage...
Not all apps, e.g. xterm seems to work, but all GNUstep applications
are affected (GS from source, not packages, but that should not matter)
Up to a couple of months ago, this was enough:
Section "Device"
Identifier "Configured Video Device"
Driver "ati"
Option "ForcePCIMode" "True"
Option "EXANoComposite" "True"
# Option "NoAccel" "True"
EndSection