Quantum is abominably bad, surpassing Chrome and Australis as two of the worst browser UIs I've ever seen. It's up there with Edge in it's clunky "hide functions from the user" levels of awful. I have TONS of screen space, stop hiding my buttons and functions behind dropdown menus and turning single-click functions into 2-4 clicks. Stop breaking must-have add-ons, stop ruining the search bar (and do NOT get rid of the search bar completely. That's a different function from the address bar and should be kept separate). This time you broke Classic Theme Restorer, which I'd no sooner use Firefox without than I would use Chrome. So the question is, when will Mozilla stop breaking the UI, and stop systematically removing options from the user to tweak their browser to their liking? Not everyone wants a UI that looks like a pretentious first-year design student with a hardon for Flat Design made it. Stop.