Raymond: yes, I am definitely open to collaboration on this issue.  The timing is good as I just started, a month ago, expanding configure dialog testing beyond the trivial one of creating an instance without raising.  Real tests are needed preparation for making other changes, including adding other new options in 3.6+.  I would like to include this one in 3.6.1, 4 to 6 months from now.

Doing so may require more information about IDLE on *nix and Mac than I currently have.  Which of those have you run IDLE on?  Or helped people with in your classes?

Nofar: welcome.  I have two immediate questions.  1) Which OS do you primarily work with?  (I am using Win 10.)  Can you test on anything else?  2) Are you only interested in this issue, or might you be open to working on other issues if this one is successful?

Idlelib is not an easy codebase to get into.  The +-60 modules are listed in README.txt.  There is also a mapping from menu items to implementation code.  However, the README does not cover the addition of a new option.  I will write and upload a design document or roadmap for this one.