Description:
Mesa produced screen artifacts with kwin and playing diablo 2 in wine

Downgrading mesa{,-dri,-libgl,-vdpau} to version 10.3.1-1 fixed the problem

Additional info:
* package version(s): mesa 10.3.2-1, xf86-video-ati 1:7.5.0-1, linux 3.17.1-1
* config and/or log files etc:
lspci | grep -i vga
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Wrestler [Radeon HD 6250]

cat /etc/X11/xorg.conf.d/20-radeon.conf
Section "Device"
Identifier "Radeon"
Driver "radeon"
Option "SWcursor" "off" #software cursor might be necessary on some rare occasions, hence set off by default
Option "EnablePageFlip" "on" #supported on all R/RV/RS4xx and older hardware, and set on by default
Option "AccelMethod" "EXA" #valid options are XAA, EXA and Glamor. EXA is the default
Option "RenderAccel" "on" #enabled by default on all radeon hardware
Option "ColorTiling" "on" #enabled by default on RV300 and later radeon cards
Option "EXAVSync" "on" #default is off, otherwise on. Only works if EXA activated
Option "EXAPixmaps" "on" #when on icreases 2D performance, but may also cause artifacts on some old cards. Only works if EXA activated
EndSection

Downgrading mesa{,-dri,-libgl,-vdpau} to version 10.3.1-1 fixed the problem

Steps to reproduce:
Upgrade to latest mesa in extra
Log in to kde with kwin as window manager
Screen artifacts will be shown (some parts of the screen would be black)