edit:@Coconutsales:
TRY "open manage groups[STG plugin]" by Drive4ik
you can put it on the right.

Great Tab Group!
enjoy manage groups in Popup, Panorama, sidebar.
switch quickly and work well.
careful in many detail

Got so much on the go that I couldn't go back to living without this extension!

Does Simple Tab Groups supports Tab Session Manager? What should I do if FF suddenly crashes? Will Tab Session Manager restore all my tabs AND GROUPS?

It works fine in a single machine, but there is no way (at least no simple way) to make it sync between different machines automatically.

Sorry, The application works slowly, especially when switching between tabs and Panorama Tab Groups. This poor performance is since the fresh installation of this extension. It should be definitely improved.
I use FF Quantum 65.0.1 (64-bit) Portable version.

Hey, thanks for making this app, it's very useful !

If you have some time, it would be nice if there was a way to move several tabs from one group to another or even merge 2 groups.

Also if you could implement a folder/file system where you can make a group of groups.

You should be able to name the tab groups and use drag-and-drop instead of going through multiple context windows. Otherwise, I'm glad I thought to look this up.

Great replacement for the old Tab Groups extensions! Wondering why is not shown as a replacement in the Tab Organizers collections along with the other ones. See https://addons.mozilla.org/en-GB/firefox/collections/4757633/tab-organizers/

Excellent add-in! I keep finding new ways to use it. Looking forward to see how it develops...

This is one of my most important add-ons, thank you very much for the great work. Browsing wouldn't be the same without it. Much appreciate your time and effort. Greetings from Germany

Transformational add-on when used with Firefox Containers. I am using about 20 groups for various clients and other activities. It makes organizing tabs much more efficient than having just one "strip" if you will. I absolutely recommend this add-on and thank to Drive4ik for making this.