Thank you Martin for your reviews. Here is updated 2.7 patch which implements your suggestion.

The disadvantage of this patch in comparison with first version is that it will not work with statically compiled embedded Python, when only stdlib is updated. I once broke re in bugfix release in such manner (by moving one constant from Python sources to C sources). On other hand, it is very unlikely that anyone uses Tkinter in such circumstances, and in any case this part of code is broken for now, so patch should not introduce new regression.