I have been setting up an Xdmx render wall. When finished it will be a 3×3 rear projected screen, with 9 computers (CentOS 5 installs) and 18 projectors for 3d visualization.
For a couple of years now Xdmx has been rolled into the Xorg source and getting it configured is really not that hard. When I have ironed out this install I may write a howto. But while some stuff was working just fine and dandy most apps that use a modern widget library for the UI (ala GTK or QT) were failing to render fonts properly, not drawing icons, messing up colors and just not looking right in general.
I scoured the interweb for answers, and the main thing I saw was just forum posts instructing users to turn of the Xorg render extension. This works, though makes the rendering of windows very, very slow. On what should be a high performance render wall I have an issue with this.
Anyway, I eventually found this post, and figured it was worth a try. And it Worked! brilliant! QT, GTK, Firefox, everything is looking peachy.
I threw it together in this patch file which I applied to the SRPM for xorg-x11-server.