Comment 2 for bug 334941

Got the following messages
Traceback (most recent call last):
  File "/usr/share/ubuntu-tweak/mainwindow.py", line 516, in setup_notebook
    page = page()
  File "/usr/share/ubuntu-tweak/compiz.py", line 202, in __init__
    self.create_interface()
  File "/usr/share/ubuntu-tweak/compiz.py", line 221, in create_interface
    hbox.pack_start(self.create_edge_setting(), True, False, 0)
  File "/usr/share/ubuntu-tweak/compiz.py", line 326, in create_edge_setting
    combobox = self.create_edge_combo_box("TopLeft")
  File "/usr/share/ubuntu-tweak/compiz.py", line 306, in create_edge_combo_box
    plugin = self.context.Plugins[k]
KeyError: 'widget'