I can't test but I looked at the patch.  It uses the new-to-me fact that bound 'functions' can be tcl code in a string.  For me, root.bind_class('Text', '<<Patch>>') returns the code string '\n    tk_textPaste %W\n'.  Options for the patch:

0. Do nothing.
1. 3.6 as option (default TBD).
2. 3.6 as fixed change.
3. All versions as option (default TBD).
4. All versions as fixed change.

I have determined that adding new sections to config-main does not affect previous releases, so 1 and 3 are possible.  See the post I just made to #27099 as to what is needed for new options.

For 1 and 3, there is the question of default - 'insert' versus 'replace', and for 3, whether it should be the same in all versions.  I don't think 'insert' and the option should stay around forever.

The question we need to think about is what would be best for beginners. The young but experienced Widows user, new to Linux, reported this to me as a bug that tripped her up a lot.

Serhiy, I think that this change, at least as an option, should be in tkinter, so as to make it more 'cross-platform'.  In the meantime, I will look at including this with the changes in #20799.

I am thinking about posting to python-ideas for other opinions on what to do in which package.