Bug for mac

[github4f]

Hi-
Chapter7.py : In mac the UI/window does not show up. However, in Ubuntu 14.04 64 bit machine with all the similar package versions but it seems that there it is working fine. Maybe this is because of gui.py or wxpython package in mac (I installed all of them using brew). Chapter3 code as well I am getting same issue.

In details, there is a infinite loop at App:init: line 1870 self._BootstrapApp() in core.py
/usr/local/lib/python2.7/site-packages/wx/core.py
Which basically tells that upon completion of this function OnInit() function will be called which should be available in derived class of App.