When starting the game "Hero Academy" in Steam for Linux, while using the Catalyst 13.12 stable driver on Arch Linxu 64bit, I get a KDE desktop with distorted graphics (see imgur-link). This happens, when the "Hero Academy" emblem shows up on the desktop and with enabled Kwin desktop effects. The emblem itself seems to be an image in a borderless window with transparent background.
Disabling the desktop effects stopps the distortion. Also this does not happen with the open-source radeon driver.