complete crap, didn't get the small 3x3 square icon on my toolbar like in the example images. no way to add it either as far as i've been able to tell. additionally this extension randomly filled the first available group(s) with my giant old bookmarks library. something i never asked it to do. which resulted in that when opening a single group in testing.
after finally having found something to access a group i made (to get my tab back), this junk immediately floods my browser with countless open tabs it also stuffed in there...

i can't understand... how difficult is it to just group up a few open tabs/pins into a single tab/pin like asked, then have this single tab show the grouped up tabs. like several other browser do already these days... it's not rocket science yet one of the few things FF sadly doesn't have, but this extension certainly doesn't help with this either...