After I added a custom Terry theme, my main activity has been tweaking it. Version 3 is an clear improvement over the existing tab.  With the example box on top, I think the comment should be
# Click here or dropbox
# below to change item.

0 Foregound 0 Background are supposed to be radio buttons.  The black and white squares look like anything but.

'Theme' is ambiguous as to Idle's text highlighting themes versus ttk's widget style themes. I think the current grouping should be labeled 'Text Highlighting'.  This will pave the way to add, to the ttk version, a 'Widget Style' listbox allowing users to choose among those available.

With these items resolved, I would be inclined to apply a tk patch to all versions.