I'm new to IDLE. I just upgraded to Mac El Capitan from Snow Leopard, and installed Python 3.5.1 (v3.5.1:37a07cee5969, Dec 5 2015, 21:12:44).
I have had the IDLE window freeze so many times (when clicking on something in the autocomplete window as described by Ned Deily) that I consider IDLE unusable. I'm not familiar with Python bug practices but I would consider this a serious bug because, as a product manager would probably put it, this is going to drive away a significant percentage of new users (i.e., unexplained freezing of the product when doing something which seems natural -- clicking on the item that I want to select).
BTW, looks like I'm on tcl 8.5:
>>> tkinter.TclVersion
8.5
Unrelated question: which can't Mac Spotlight find tkinter.py? is it in some compressed file or something, so I can't find a standalone py file?