Example program needs a toolbar set on app.main_window

[evanbrumley]

Just tried this out on Ubuntu 12.04, and the example program raises the following exception;

Traceback (most recent call last):
    File "/home/evan/.virtualenvs/psmove_toga/local/lib/python2.7/site-packages/toga/platform/gtk/app.py", line 27, in _startup
    self.main_window.app = self
  File "/home/evan/.virtualenvs/psmove_toga/local/lib/python2.7/site-packages/toga/platform/gtk/window.py", line 61, in app
    self._startup()
  File "/home/evan/.virtualenvs/psmove_toga/local/lib/python2.7/site-packages/toga/platform/gtk/window.py", line 24, in _startup
    if self.toolbar:
AttributeError: 'MainWindow' object has no attribute 'toolbar'

Adding this seems to fix the problem:

app.main_window.toolbar = []

[freakboy3742]

Thanks for the suggestion. However, I see this as a bug in the code, not the tutorial. You shouldn't need to explicitly specify "there's no toolbar".

[freakboy3742]

Oops - sorry - commented on the bug report, not the pull request. Thanks for the report!