The button chopped off happened to me yesterday and today, I am using FF.
Version 16.
WB 7.1, or 7.3.
Odd, after metal tech did it, I installed my Necro, and it to did it, but just in FF maximized. Other windows are fine.
My new skin works okay also, and has no extensions to framing, basically square, no sticky outys!
Maybe an issue with framing and margins settings not loading correctly, leave that to the code masters.
Hope it gets straightened out, kinda sucks.
Gotta be a similarity with what is causing it seeing how we use different everything proggie ways, wb code or FF code. I wish yous luck.