wx._core.PyApp:
The ``wx.PyApp`` class is an *implementation detail*, please use
the `wx.App` class (or some other derived class) instead.
wx._core.App:
The ``wx.App`` class represents the application and is used to:
* bootstrap the wxPython system and initialize the underlying
gui toolkit
* set and get application-wide properties
* implement the windowing system main message or event loop,
and to dispatch events to window instances
* etc.