The fact that Tab indents regions as well as lines seems not be documented. This should be added to Automatic Indentation (which should just be Indentation) with BackTab doc addition if not sooner.

On Windows, 3.4.1, shift-tab is the same as tab. The same is true in Notepad (not a model to follow), but Notepad++ dedents. Doing the same in Idle, within the editor, seems like a reasonable request.

The unplanned and strange OSX behavior should be fixed.

From the patch, I would gather that the problem is that tk hard-codes shift-Tab to <<prev-window (and, I would expect, tab to <<next-window>>). (This works but is currently useless in the dialogs.) If that is so, why do they currently act the same (for me) in the editor? Does tk automatically rebind Tab to indent-region in a text widget?

Tal: option 2 seems like something to try. If Shift-Tab is user configurable (and I think baked-in like Tab would be ok), then it should be *added* in both places. You might be right about break, except this is a moot point if the code is wrong.