The next blockers are the tests for the other 3 tabs: #31001, #31002, #31093.  

Steps for converting block of ConfigDialog methods for tab X into a class.  Steps are updated from #31050.

* In create_widgets, change 'self.create_page_/highlight/keys/extensions/' to '/High/Keys/Ext/Page(note)'.
* In load_configs, comment-out load_X_cfgs.  If there is no problem moving all these calls into the class inits, method will be deleted.
* Copy the block for X into its appropriate position after class FontPage.
* Comment out old code.
* Before the copy, add 'class XPage(Frame):' and def __init__ as given in the outline.
* In the 'create_page_x' method, at the top, Pass 'self' instead of 'parent' as tk Var masters;
* delete 'frame = dialog.tabpages...';
* replace 'frame' with 'self' as master for widgets that used 'frame';
* delete 'return frame' at end.

After tests pass with revision above, delete original block of methods.

I have considered doing this before writing tests, but I don't quite feel comfortable doing so.  To convert tests written first:

* change 'XTest' to 'XPageTest' where 2nd X is abbreviated form.
* change setUpClass similarly as in FontPageTest;
* change test functions similarly as in FontPageTest; change 'dialog' to 'self.page' and 'd = dialog' to 'd = self.page'.
* make other changes needed to keep tests passing, but there may not be any more changes needed.