Put the AquaTk code added to pyshell.main in #24801 where it should have gone originally. (My fault, ultimately.)  See aqua_context.diff.  This is a step in factoring main (currently about 170 lines) into a manageable number of function calls.

I will try to add a test that 1. creates an editor window with a 'fixed' root and mocked .right_click_event method, generates a right click, and checks the mock event handler; 2. creates a context menu, etc.

Serhiy, the docstring for .class_bind says "Bind to widgets with bindtag CLASSNAME".  I have not and do not see 'bindtag' defined.  Am I correct that it must refer to a tk widget class, rather than a python tkinter class, or subclass thereof?