idlelib.configdialog uses the British spelling 'colour' instead of the American spelling 'color' everywhere except for externally mandated import and parameter names and in some recent comments. idlelib uses 'color' everywhere else. # change 'colour' to 'color' in idlelib.configdialog 3.6 with open('F:/python/dev/36/lib/idlelib/configdialog.py', 'r+') as f: code = f.read().replace('Colour', 'Color').replace('colour', 'color') f.seek(0); f.truncate() f.write(code) produces the attached patch. I would like to apply this before 3.6.0rc. I might wait until a week before that in case I want to backport any configdialog changes to 3.5. (Any such changes might require regenerating the patch.)

Offtopic. I would suggest you to install GNU sed. From GnuWin [1] or as a part of Cygwin distribution [2]. 4-line Python script can be replaced with one simple command: sed -i -re "s/([Cc])olour/\1olor/g" configdialog.py [1] http://gnuwin32.sourceforge.net/packages/sed.htm [2] http://cygwin.com/

Hmmm. I believe the Win10 Anniversary Update is supposed to include the new Ubuntu-bash-linux subsystem. I presume it should include sed. I need to see if I have the update and the subsystem, and what it includes. I could have done this one, within one file, with replace-all. But I expect to be doing some multifile name changes, and I presume sed will do that. I decided to apply this tomorrow after re-checking the changes. I checked current configdialog issues and decided not to worry about backports. Planned and proposed cosmetic fixups -- PEP8 renamings, ttk replacements (see #27755, for instance), and revised layouts will be bigger issues. And I want to start on these next.

 New changeset a54a8f188a803cd41bdc8758c10d34ba3328c566 by Terry Jan Reedy in branch 'master': bpo-28523: IDLE: Use 'color' instead of 'colour'. (#2787) https://github.com/python/cpython/commit/a54a8f188a803cd41bdc8758c10d34ba3328c566 

 New changeset ac5c1e2ea311d11714f89476c86936f9388d19a4 by Terry Jan Reedy in branch '3.6': [3.6] bpo-28523: IDLE: Use 'color' instead of 'colour'. (GH-2787) (#2791) https://github.com/python/cpython/commit/ac5c1e2ea311d11714f89476c86936f9388d19a4