kivy backtrace

gistfile1.txt

 Traceback (most recent call last):
   File "[...]/main.py", line 120, in <module>
     main()
   File "[...]/main.py", line 117, in main
     MainApp().run()
   File "/usr/local/lib/python3.3/dist-packages/kivy/app.py", line 792, in run
     runTouchApp()
   File "/usr/local/lib/python3.3/dist-packages/kivy/base.py", line 481, in runTouchApp
     EventLoop.window.mainloop()
   File "/usr/local/lib/python3.3/dist-packages/kivy/core/window/window_pygame.py", line 381, in mainloop
     self._mainloop()
   File "/usr/local/lib/python3.3/dist-packages/kivy/core/window/window_pygame.py", line 287, in _mainloop
     EventLoop.idle()
   File "/usr/local/lib/python3.3/dist-packages/kivy/base.py", line 330, in idle
     Clock.tick_draw()
   File "/usr/local/lib/python3.3/dist-packages/kivy/clock.py", line 429, in tick_draw
     self._process_events_before_frame()
   File "/usr/local/lib/python3.3/dist-packages/kivy/clock.py", line 562, in _process_events_before_frame
     if event.tick(self._last_tick) is False:
   File "/usr/local/lib/python3.3/dist-packages/kivy/clock.py", line 309, in tick
     ret = callback(self._dt)
   File "/usr/local/lib/python3.3/dist-packages/kivy/uix/boxlayout.py", line 175, in do_layout
     c.width = w
   File "properties.pyx", line 345, in kivy.properties.Property.__set__ (/tmp/pip_build_root/kivy/kivy/properties.c:3588)
   File "properties.pyx", line 377, in kivy.properties.Property.set (/tmp/pip_build_root/kivy/kivy/properties.c:4063)
   File "properties.pyx", line 431, in kivy.properties.Property.dispatch (/tmp/pip_build_root/kivy/kivy/properties.c:4656)
   File "/usr/local/lib/python3.3/dist-packages/kivy/uix/actionbar.py", line 548, in on_width
     self._layout_all()
   File "/usr/local/lib/python3.3/dist-packages/kivy/uix/actionbar.py", line 433, in _layout_all
     super_add(self.action_previous)
   File "/usr/local/lib/python3.3/dist-packages/kivy/uix/boxlayout.py", line 211, in add_widget
     widget.bind(
 AttributeError: 'NoneType' object has no attribute 'bind'