Rethinking about the changes done in Misc._configure I found out that
you don't need any of those there. 
Isn't it the case of only improving the changes regarding callable
overwriting in Misc._options ? So if the value is a callable and the
option doesn't exist you also don't _register the callable. Maybe I'm
forgetting about something here, so you could bring an example that
fails on this reasoning.

I've applied these changes and others commented before in a thing I'm
testing:
http://code.google.com/p/plumage/source/detail?r=85
http://code.google.com/p/plumage/source/detail?r=86
http://code.google.com/p/plumage/source/detail?r=87
http://code.google.com/p/plumage/source/detail?r=89
http://code.google.com/p/plumage/source/detail?r=91

I didn't fix the ones related to Variable yet, but if any of these
changes looks fine for someone the diffs would probably apply on "the
standard" Tkinter.py without much problem.