PR title and blurb only refer to Escape to exit (cancel). I may limit PR to this, but expand to subsidiary dialogs that are not query boxes. (Should check code since it works.)

If there is a key for [Apply], there should be a key for [OK].
Ctrl-Enter and Alt-Enter might be a good pair.

Tab navigation has multiple problems: Never gets to these buttons.
Tabbing into font sample traps focus on the text widget.
Some widgets get skipped.

Other key bindings are needed: No way to toggle button or select radio button.

Changes are needed, but I am not sure which to do at the moment.