Attached is a diff which moves the logic for `setup_master` to the tkinter module while allowing it to still be imported from the tkinter.ttk module (in case someone uses it...) The diff also replaces the logic in a few other places to:
A. make behaviour more consistent
B. give nicer errors in other methods (i.e. avoiding what this issue is about but in other places)

I guess my question is whether we are limiting most changes to just __init__.py or whether we want to do more of a cleanup throughout the tkinter module (e.g. tkinter.dialog.Dialog can be neatened and no longer needs to inherit the Widget class).