A little further investigation locally gives the following. 0x2b1 doesn't really look like a valid pointer.
(gdb) f 0 #0 0xb76bd671 in wobblyHandleEvent (d=0x8076800, event=0xbff71528) at ../../plugins/wobbly.c:2168 2168 WOBBLY_WINDOW (ws->grabWindow); (gdb) print ws->grabWindow $1 = (CompWindow *) 0x854e010 (gdb) print ws->grabWindow->screen->display $2 = (CompDisplay *) 0x2b1
A little further investigation locally gives the following. 0x2b1 doesn't really look like a valid pointer.
(gdb) f 0 wobbly. c:2168 >screen- >display
#0 0xb76bd671 in wobblyHandleEvent (d=0x8076800, event=0xbff71528) at ../../plugins/
2168 WOBBLY_WINDOW (ws->grabWindow);
(gdb) print ws->grabWindow
$1 = (CompWindow *) 0x854e010
(gdb) print ws->grabWindow-
$2 = (CompDisplay *) 0x2b1