There was a whole experiment with this "Tab Candy" thing a few years ago. And it failed and Mozilla disabled it and it got silently removed, well, almost, becau

There was a whole experiment with this "Tab Candy" thing a few years ago. And it failed and Mozilla disabled it and it got silently removed, well, almost, because a fair amount of people complained. I wouldn't be surprised if today's tab groups go the same way. Browser innovation is hard and at this point most of the innovation is in forks of Firefox, rather than Firefox itself.