Created attachment 78244 [details]
Dualdisplay bug.

Hello,

with radeon driver and mesa in version 9.1.1 I have problem with switching
display between notebook and external display in KDE 4.10.2 with kwin_gles
compositor in compositing type OpenGL.

Setting dual display (left/right/above) or switching between displays, causes
broken screen. Please, check attached screenshot.

Downgrading to mesa version 9.0.2 solve this problem. 

With intel GPU/Driver is everything OK.

KDE version 4.10.2
GPU: ATI x1400, driver - radeon
Kernel: 3.8.7
mesa version: 9.1.1
ati-dri version: 9.1.1