Here's a new version of the patch, post-#22236.  Serhiy, since you want this in 2.7 and 3.4, this version doesn't move any files around (except Lib/test/test_tcl.py), which should make backporting easier.

I like this patch much better than the original, it's a much smaller diff and doesn't have to mess around with a 'setUpGUIModule' function.

The desegregation of test_tcl, test_tk, test_ttk_guionly and test_ttk_textonly is intentional: with the patch, all of the tests that require the gui are properly guarded by test.support.requires('gui'), and the ttk gui tests are additionally guarded by the new 'tkinter.test.support.check_ttk_availability' function (which I still have yet to test against Tk 8.4, but plan to shortly).  This means that by doing 'python -m test test_tkinter', all gui-less tests are run (namely, the current test_tcl and test_ttk_textonly, and also test_variables) and all the gui tests are reported as skipped.  Meanwhile, doing 'python -m test -uall test_tkinter' or 'python -m tkinter.test', all 935 tkinter tests are run (if a gui is in fact available).  Currently, the shortest invocation for running all of the tkinter tests that I know of is 'python -m test -uall test_tcl test_tk test_ttk_guionly test_ttk_textonly', which is quite a handful to type every time :).  If you really want the old subsets, they're still available as 'python -m tkinter.test.test_(tcl|tkinter|ttk|ttk.test_functions)' (though 'tkinter.test.test_ttk' will also run the 'ttk_textonly' tests).