“run ``import idlelib; idlelib.run`` within a try-except statement”: It might be nice to say what exceptions are expected. My guess is ImportError if Idle or TK is not available, or AttributeError if it is but Idle is not running.

“Tk handling of ascii control chars”: I presume you mean stdout and stderr handling, which this bug was originally about (or also input, source code, etc as well?). It might be good to say that output of Unix newlines (\n) is guaranteed to be supported. Also might be worth explicitly pointing out that output of CRLFs is not supported, even if os.linesep is "\r\n". In my experiments between Linux and Wine, this does not appear to depend on the OS.