The problem is spotting the start of a logical grouping in many tabs open at once in a window. I arrange them in order when researching something. So, there's 20 tabs open, 4 different categories of the subject topic. There has to be a way besides a sidebar, to signify fast which group starts where. Best case scenario would be marking the 1st tab of a group with a flag, or static pop-up - a short, 15 character-limit description to signify which group it is (like '4k', '1080p', '720p', for video resolution values). 2nd-best would be a mouse-hover message, i.e. a flag or balloon to pop-up with the 15-character description. Finally, I could color-code the 1st tab of a group, or even the text .I saw some good extensions that did these - looks like Firefox disabled them with the latest browser upgrade. Are there any cross-browser or Firefox persistent apps or add-ons that will let me mark up individual tabs, with either icons, messages, or background colors?