Experiments are good, even if not accepted as is.
Python uses American spellings: so 'Colors'.
Moving help sources frees up enough vertical space to reduce the pressure to split General.  It would again fit vertically on my Mac Airbook.
'Windows' is really 'Shell&Editor'.  'Blink' is the only thing that really applies to grep output windows.  'Windows' will not apply if we make IDLE multi-tabbed.

The collage showing all pages at once is useful.  I really want to spread the dialog horizontally a bit.  The font sample could be wider.  Colors and keys should have a uniform simplified theme/keyset selection box and other misc stuff on the left and a text or list box on the right.  The cfg_highlight_alt.png and highlight3.png on issue 24781 are similar except that the left selection box should only be as big as needed (default 3) and the text is now bigger.  So other stuff, possibly revised, should likely be on the left.

Most of the General entries can be shrunk to 50-60% of the current width, or else wrapped.  Example:
  At startup, open ()Shell  ()Editor
  <For match stuff, put []bell on new line>

> split the "Extensions" page into its own class
This was intended: issue 31207.  I guess we ran out of gas before this.  We could even consider extension and help frame classes besides the help/ext page class.

Possible order of changes.

#31207: ExtPage class and tests
new: move Help sources to ExtPage and tests (to own testcase)
new: move indent (as int entry box) and test to general.  Add help note that indent is used to indent tab adds, indent delete backspaces, and smart indents.
List issue on #24776 where indent discussed.
#24781: Colors (see discussion above)
new: Keys
this? or new: redo General

At some point, list classes in configdialog and test_configdialog. docstring so know what names to search for to find them.

There are several other configdialog issues to fix glitches or make small improvements here and there.