Description of problem: On bootup, KDM loads and looks OK. After I login and logout, the KDM window is transparent (the desktop backround is there instead of the gray window background). The buttons and the session type box look OK. I'm using the High Color theme for KDM, "standard" font size changed from 12 to 11 points, Czech locale. I should mention this is on ATI r128, which has other problems (elsewhere in bugzilla), but this is too simple and too reproducible, so I think this is not related (I have no other machine to test it on).
Sorry, turning DRI off cures it. So it's the ATI thing. *** This bug has been marked as a duplicate of 64503 ***