Hello. I just upgraded my OS. The upgrade included Firefox v60.0 which replaces the window manager, which I find unacceptable. Not only is this highly irritating because I use the 'Close' button on the left (and Firefox has it on the right) it also messes up the appearance (colours, transparency, icons, etc.) but also removes some of the window manager's functionality (shade, focus model, keyboard shortcuts, etc.). How do I disable this "feature" so that I can use my system the way I want to instead of being dictated by Mozilla how I should use it? Thank you kindly.