RadioBox in a menu: single line instead of multiple rows

The demo code is part of the wxPython demo application. Therefore it uses wrapped code to fit into that “framework”.

Look here on how you might adapt a single demo source to run independently from the main demo app.

https://wiki.wxpython.org/Using%20wxPython%20Demo%20Code

You should also be better off when downloading the demo - see topic Demo Application.

Then run:

<YourLocalPythonRootDir>/Lib/site-packages/wxPython-demo/demo.pyw