I haven’t used combo_box extensively but I’m all for extending the built-in widgets with more advanced features that may be too niche to warrant inclusion directly in the library.
So much so that I’ve created a crate for that specific purpose:
It’s mean to be open and welcoming to contributors, so if you’d like to put up your modified combo_box there, that would be awesome.
Right now it only has a modified mouse_area which returns the cursor position when clicked and a modified pick_list with optional disabling of elements, but I have a few other ideas of my own in the works and one potential slider improvement that allows for multiple handles in a single slider (which was written by someone else!)