#6665 for bpo-33397 defines a FontSizer class in textview.py and uses it for textviews and the help viewer. I intend for it to be used everywhere for key/wheel font resizing, especially including editor windows. So as is, this PR duplicates the work there and needs to be either rewritten or replaced.

You could help by reviewing that code and testing it on your system, and even better, copying the new textview into your branch (or a new one) and trying to use it for the editor.

Editor font resizing must also change the context window if present and the line number window if present. There should be a function that does that, but it might be hard-coded to use the general config values.

Changing configdialog font sizing is bpo-24776. My latest plan for that (msg334281) is to use the font sizer (or subclass) to change both the font sample and the number is a box.