unity-window-decorator crashed in window_closed() with SEGV

Program received signal SIGSEGV, Segmentation fault.
(gdb) thread apply all bt

Thread 2 (Thread 0xb7da7b70 (LWP 4061)):
#0 0x0012e416 in __kernel_vsyscall ()
#1 0x00acad96 in poll () from /lib/libc.so.6
#2 0x0095d8cb in g_poll () from /lib/libglib-2.0.so.0
#3 0x0094d30f in ?? () from /lib/libglib-2.0.so.0
#4 0x0094da93 in g_main_loop_run () from /lib/libglib-2.0.so.0
#5 0x00c202d4 in ?? () from /usr/lib/libgio-2.0.so.0
#6 0x0097638f in ?? () from /lib/libglib-2.0.so.0
#7 0x00cc7e99 in start_thread () from /lib/libpthread.so.0
#8 0x00ad95fe in clone () from /lib/libc.so.6

Thread 1 (Thread 0xb7fd5880 (LWP 4058)):
#0 window_closed (screen=0x80cb410, win=0x8151738) at /build/buildd/compiz-0.9.4/unity/unity_window_decorator/src/wnck.c:725
#1 0x008ee088 in g_cclosure_marshal_VOID__OBJECT () from /usr/lib/libgobject-2.0.so.0
#2 0x008d1352 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#3 0x008e4048 in ?? () from /usr/lib/libgobject-2.0.so.0
#4 0x008ecb29 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#5 0x008eccc2 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#6 0x002a25ca in emit_window_closed (screen=0x80cb410) at screen.c:2417
#7 update_client_list (screen=0x80cb410) at screen.c:1771
#8 do_update_now (screen=0x80cb410) at screen.c:2332
#9 0x002a2c78 in update_idle (data=0x80cb410) at screen.c:2355
#10 0x00948451 in ?? () from /lib/libglib-2.0.so.0
#11 0x0094cc08 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#12 0x0094d3d0 in ?? () from /lib/libglib-2.0.so.0
#13 0x0094da93 in g_main_loop_run () from /lib/libglib-2.0.so.0
#14 0x003f7a49 in IA__gtk_main () at /build/buildd/gtk+2.0-2.24.1/gtk/gtkmain.c:1256
#15 0x0804f5d0 in main (argc=1, argv=0xbffff424)
    at /build/buildd/compiz-0.9.4/unity/unity_window_decorator/src/gtk-window-decorator.c:440

(gdb) print *win
$1 = {parent_instance = {g_type_instance = {g_class = 0x812eea0}, ref_count = 2, qdata = 0x81a9f40}, priv = 0x8151748}

(gdb) print *screen
$2 = {parent_instance = {g_type_instance = {g_class = 0x80ca508}, ref_count = 2, qdata = 0x0}, priv = 0x80cb420}