Thanks for the report. I added Ned since it seemed similar to issue32481 but  from Python 3.7 the Mac installers from python.org ship with in-built Tcl/Tk 8.6.8 as in which was the reported version https://www.python.org/download/mac/tcltk/#built-in-8-6-8 . I was able to reproduce the crash with attached file on 3.6 which was installed from Homebrew. I was not able to reproduce the crash on Python 3.7.1RC2 installed from python.org. I don't know if installing 3.7 from Homebrew might cause problems with my existing virtual environments to validate my assumption.

1. @remi_bertholet Is Python 3.7 installed with Homebrew? 
2. Ned, does Python 3.7 that is installed from Homebrew ship with in-built Tcl/Tk similar to Mac installers from python.org?