My idea is to centralize decisions on this area and make any architectural changes documented and explicit. Feel free to comment.

For new mxGraph users, compatibility is not an issue, but for existing ones, introducing too much changes in one step could be challenging.

Starting point: #1 (comment)

I don't intend to maintain backwards compatibility for all of the modules as I think there needs to be some architectural changes to keep the codebase maintainable going into the future, but the structure+functionality of mxGraph overall seems fairly well thought out as-is in my opinion, even if it uses an older JS code style. I think I will probably keep the class names and function parameters etc the same for the most part.

Notably, I have already removed support for VML/Internet Explorer and Edge before it shifted to the Chromium engine, as I think that significantly eases maintenance.