@joyboy I know it's not the same thing but give tab containers a try. It's build in to firefox. Just click and hold the new tab button.But still separate profiles in separate windows is superior for me. Firefox has that capability out of the box, but...
Build in Media Controller
Build in Media Controller like the one in Chrome or exactly like that add-on: https://addons.mozilla.org/en-GB/firefox/addon/mcx/Thumbnail of the VideoPause and resume playbackSkip forward and backwardJump to tab when clicki...
Build in Profile Switcher
A build in and easy to use profile switcher would be great.There is already a addon called "Profile Switcher for Firefox" from nulldev. Maybe it's possible to implement it or something similar directly into the browser?