On my ATI Mobility X1600 [M56] (Acer TravelMate 8200), when using the latest radeonhd driver from git or even stable 1.0.0, I have a verticle garble of video in the center of my screen (1680x1050) and another to the upper right location of my screen.
I am not very knowledgeable about Xorg and the different settings so my initial thoughts are likely not the case, but for the 2 cents, I think it might have to do with xrandr reporting h-sync or v-sync's inappropriately.
I would love to help find the solution to this problem as I am sure it probably exists for someone else too.
Right, another one of the known issues. This is a linebuffering problem that many people are complaining about, and we will look into this.
We believe this to be a highly related issue to the flickering mousecursor. Both seem to imply memory starvation of the grph/cur engines.
*** This bug has been marked as a duplicate of bug 13405 ***