I use KDE 4...
Sounds suicidal? Go check your facts. Anyway, I use Mesa 7.7 for 3D, plus libdrm and the X.org radeon driver from their git repositories. The system is Debian Squeeze, but it's a few weeks behind testing because I've not had access to a strong connection to download the shitload of packages (~350 MB) for upgrading.
I found that if I open Konqueror's bookmarks menu, when it has many more elements than they fit in the whole screen, X.org crashes!
Backtrace: 0: /usr/bin/X(xorg_backtrace+0x26) [0x4ee056] 1: /usr/bin/X(xf86SigHandler+0x39) [0x484199] 2: /lib/libc.so.6 [0x7ffc172e8fd0] 3: /usr/lib/dri/r600_dri.so(r600SetTexOffset+0x8b) [0x7ffc028e306b] 4: /usr/lib/xorg/modules/extensions//libglx.so [0x7ffc163b911c] 5: /usr/lib/xorg/modules/extensions//libglx.so(__glXleaveServer+0x18) [0x7ffc163affa8] 6: /usr/lib/xorg/modules/extensions//libglx.so [0x7ffc163b055f] 7: /usr/bin/X(Dispatch+0x374) [0x44d494] 8: /usr/bin/X(main+0x3aa) [0x43337a] 9: /lib/libc.so.6(__libc_start_main+0xfd) [0x7ffc172d5abd] 10: /usr/bin/X [0x432819] Fatal server error: Caught signal 11. Server aborting
It reproduces with the Oxygen theme too. All with KDE 4.3.2 — but the crash seems to come via Mesa 7.7's ATI R6xx/R7xx DRI driver. Ah, yays for newborn drivers.