Created attachment 137087 [details] [review]
Possible fix, tested against server 1.19 branch.

This patch fixes the problem with compton, as tested against server 1.19
branch. Also applies cleanly against master, but i haven't tested it on master
yet.

So far tested with KDE-5, compiz, and compton, on ati-ddx under Radeon gfx,
both screen depth 24 and 30.