Strangely enough, running hgk (a port of gitk to Mercurial, also known as hg view) with Tk 8.4 crashes my X server. Updating both Tk and the X doesn't help. I don't feel like I want to debug X now, but probably that's what I have to do :(
Backtrace: 0: /usr/bin/X (xorg_backtrace+0x49) [0xb7712ed9] 1: /usr/bin/X (0xb7572000+0x1a4c64) [0xb7716c64] 2: linux-gate.so.1 (__kernel_rt_sigreturn+0x0) [0xb755040c] 3: /lib/i386-linux-gnu/i686/cmov/libc.so.6 (0xb711d000+0x772f0) [0xb71942f0] 4: /lib/i386-linux-gnu/i686/cmov/libc.so.6 (__libc_calloc+0xab) [0xb7196d5b] 5: /usr/bin/X (0xb7572000+0x55ca9) [0xb75c7ca9] 6: /usr/bin/X (0xb7572000+0x48005) [0xb75ba005] 7: /usr/bin/X (0xb7572000+0x491c3) [0xb75bb1c3] 8: /usr/bin/X (0xb7572000+0x12c621) [0xb769e621] 9: /usr/bin/X (XkbHandleActions+0x20b) [0xb76c8c1b] 10: /usr/bin/X (XkbProcessKeyboardEvent+0xbc) [0xb76c937c] 11: /usr/bin/X (AccessXFilterPressEvent+0xcd) [0xb76c181d] 12: /usr/bin/X (0xb7572000+0x157675) [0xb76c9675] 13: /usr/bin/X (mieqProcessDeviceEvent+0x1e6) [0xb76f3226] 14: /usr/bin/X (mieqProcessInputEvents+0xfd) [0xb76f335d] 15: /usr/bin/X (ProcessInputEvents+0x14) [0xb75ef3e4] 16: /usr/bin/X (0xb7572000+0x3c25d) [0xb75ae25d] 17: /usr/bin/X (0xb7572000+0x2a51a) [0xb759c51a] 18: /lib/i386-linux-gnu/i686/cmov/libc.so.6 (__libc_start_main+0xf5) [0xb71368c5] 19: /usr/bin/X (0xb7572000+0x2a8f8) [0xb759c8f8]