Ned, many thanks for the review and detailed feedback!

Here are responses to your comments

1. Thanks for the code suggestion regarding the menudefs! That's a good catch. I have an OSX box for such testing.

2. I'll check this out. Could you perhaps explain or point me to resources regarding how to run IDLE with various Tk implementations on OSX?

3. Unfortunately, IDLE's config mechanism doesn't have special support for options with only several valid values, as would have been ideal for ParenMatch's "style" parameter. As it is, these are just considered strings, and no explicit error occurs if an invalid value is specified. Without upgrading the config mechanism itself, the config dialog has no way of supplying the valid values and/or validating user input of such values. This could be useful, but should be considered a separate issue IMO. I would be happy to add relevant support to the dialog once the underlying support is implemented.

4. Regarding having thing updated only on new windows or after restart, AFAIK that is currently the case with many options in the existing config dialog. Ideally the behavior would be consistent for all config options, and even more ideally all config changes would take effect immediately. However, that would require major changes to IDLE. Again, I think this is outside the scope of this issue.

5. I completely agree that the button for boolean options looks horrible. Suggestions for a better Tk widget to use are welcome!

Finally, regarding