Comment 2 for bug 865836

Heres the terminal output whenever it fails to remove a window from the list:

    Traceback (most recent call last):
      File "/usr/local/lib/python2.7/dist-packages/dockbarx/dockbar.py", line 475, in __on_window_closed
        dock.remove_window(window)
      File "/usr/bin/dockx", line 930, in remove_window
        del self.border_distances[window]
      File "/usr/lib/python2.7/weakref.py", line 253, in __delitem__
        del self.data[ref(key)]
    KeyError: <weakref at 0x367ecb0; to 'wnck.Window' at 0x39e44b0>