Comment 65 for bug 727143

Hope this helps:

(unity-window-decorator:6151): GLib-GObject-CRITICAL **: g_object_get_data: assertion `G_IS_OBJECT (object)' failed

(unity-window-decorator:6151): GLib-GObject-CRITICAL **: g_object_get_data: assertion `G_IS_OBJECT (object)' failed

(unity-window-decorator:6151): GLib-GObject-CRITICAL **: g_object_get_data: assertion `G_IS_OBJECT (object)' failed

(unity-window-decorator:6151): GLib-GObject-WARNING **: invalid uninstantiatable type `(null)' in cast to `GObject'

(unity-window-decorator:6151): GLib-GObject-CRITICAL **: g_object_get_data: assertion `G_IS_OBJECT (object)' failed

Program received signal SIGSEGV, Segmentation fault.
window_closed (screen=<value optimised out>, win=0x7b40d0) at /build/buildd/compiz-0.9.4+bzr20110415/unity/unity_window_decorator/src/wnck.c:723
723 /build/buildd/compiz-0.9.4+bzr20110415/unity/unity_window_decorator/src/wnck.c: No such file or directory.
        in /build/buildd/compiz-0.9.4+bzr20110415/unity/unity_window_decorator/src/wnck.c
(gdb) bt
#0 window_closed (screen=<value optimised out>, win=0x7b40d0) at /build/buildd/compiz-0.9.4+bzr20110415/unity/unity_window_decorator/src/wnck.c:723
#1 0x00007ffff4ed581c in g_closure_invoke () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#2 0x00007ffff4ee7019 in ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#3 0x00007ffff4ef0258 in g_signal_emit_valist () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#4 0x00007ffff4ef041f in g_signal_emit () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#5 0x00007ffff7228d44 in ?? () from /usr/lib/libwnck-1.so.22
#6 0x00007ffff72293d4 in ?? () from /usr/lib/libwnck-1.so.22
#7 0x00007ffff4609bcd in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#8 0x00007ffff460a3a8 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#9 0x00007ffff460a9f2 in g_main_loop_run () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#10 0x00007ffff6d04af7 in gtk_main () from /usr/lib/libgtk-x11-2.0.so.0
#11 0x0000000000409864 in main (argc=2, argv=0x7fffffffe278)
    at /build/buildd/compiz-0.9.4+bzr20110415/unity/unity_window_decorator/src/gtk-window-decorator.c:440