> Ned, Mark will be opening several appearance issues (see ttk thread on Idle
> list).  Do you want to be routinely added as nosy to comment?

No, that's not necessary or desirable.  At the moment, I don't think I have much bandwidth or expertise to contribute to appearance discussions.  I'll chime in if asked or if anything strikes me.

As a general principle, do keep in mind that for each current actively maintained Python release (e.g. 2.7, 3.4, and 3.5), on python.org we supply two Python installer variants for OS X: (1) for OS X 10.6 and higher that links with Tcl/Tk 8.5 and (2) for OS X 10.5 (and higher, although intended primarily for 10.5) that links with Tcl/Tk 8.4.  So any changes for IDLE for 2.7, 3.4, and 3.5 should work across all of those combinations of OS X releases and Tk versions.  (For Python 3.6, I'd like to move to shipping with just Tk 8.6, if possible.)  Also, there are third-party distributors of Python for OS X that currently link with Cocoa Tk 8.6 and with X11 Tk 8.6, for example, MacPorts.

https://www.python.org/download/mac/tcltk/