Using xf86-video-ati-6.6.192 (patched with fixes from bug #10772) krandrtray make it segfaults when trying to change the resolution:

(...)
(**) RADEON(0): RADEONSaveScreen(2)
(**) RADEON(0): RADEONSaveScreen(2)
(**) RADEON(0): RADEONSaveScreen(2)

Backtrace:
0: /etc/X11/X(xf86SigHandler+0x85) [0x80c46e5]
1: [0xffffe420]
2: /etc/X11/X(RRCrtcSet+0x2a) [0x816a91a]
3: /etc/X11/X(ProcRRSetScreenConfig+0x600) [0x816f8d0]
4: /etc/X11/X [0x81692a3]
5: /etc/X11/X [0x81527f7]
6: /etc/X11/X(Dispatch+0x1af) [0x8089d6f]
7: /etc/X11/X(main+0x465) [0x8071025]
8: /lib/i686/libc.so.6(__libc_start_main+0xe0) [0xb7cbff90]
9: /etc/X11/X(FontFileCompleteXLFD+0x1e5) [0x80703a1]

Fatal server error:
Caught signal 11.  Server aborting

(II) AIGLX: Suspending AIGLX clients for VT switch
(**) RADEON(0): RADEONLeaveVT
(**) RADEON(0): EngineRestore (32/32)
(**) RADEON(0): RADEONRestore
(**) RADEON(0): RADEONRestoreMode(0x8238bc8)
(**) RADEON(0): RADEONRestoreMemMapRegisters() : 
(**) RADEON(0):   MC_FB_LOCATION   : 0x1fff0000
(**) RADEON(0):   MC_AGP_LOCATION  : 0x27ff2000
(**) RADEON(0):   Map Changed ! Applying ...
(**) RADEON(0):   Map applied, resetting engine ...
(**) RADEON(0): Updating display base addresses...
(**) RADEON(0): Memory map updated.
(**) RADEON(0): Programming CRTC2, offset: 0x00000000
(**) RADEON(0): Wrote: 0x00000000 0x00000000 0x00000000 (0x0000a400)
(**) RADEON(0): Wrote: rd=0, fd=0, pd=0
(**) RADEON(0): Programming CRTC1, offset: 0x00000000
(**) RADEON(0): Wrote: 0x0000000c 0x00030065 0x00000000 (0x0000a400)
(**) RADEON(0): Wrote: rd=12, fd=101, pd=3
(**) RADEON(0): Ok, leaving now...