Was great, now constantly flashes "Session did not match and will not save. Click here to reload" and automatically reloads the sidebar every second or so. Completely unusable right now. Seems to be a common theme.

EDIT: I do start with previous session. After ticking that option and restarting FF, the sidebar loaded ok. un-checked it, opened a few tabs, restarted again, and all is still good. Back to 4 *.
Will rate 5 if you give an option to not flash the 'tabs saved' text at the bottom. it is always catching my eye and distracting me.

Doesn't work, the tabs list is reloading every second and it's unusable

Edit: author provided a fix for the bug

Just installed this. looks like it will be super-useful. I did spend time clicking on all the menu buttons, but still unclear on:
1) how to set up groups and folders and how they differ from each other.
2) how to color individual tab rows
Is there any type of User Guide anywhere??
Thank you.

1. sometimes add-on is loosing the sorting of tabs and all tabs appears in "ungrupped" tab
2. two time add-on losed open tabs at all
3. almost always add-on restores the closed tab in the wrong place where the tab was closed. Mostly the tab is restored at the beginning of the next group
4. there is a problems with a focusing on tabs when current tab was closed

so.. it's raw

It's the best addon for tab management, in my opinion. It has groups and folders , autosave(Tools=>Open Window Manager=>Autosave) and import/export sessions feature. If one "loses" its groups folders, it is really easy to get them back by loading and merging a previous (working) session into the current one through the autosave feature mentioned above. Previously i have tried Tab Center Redux then TreeStyleTabs + SimpleTabGroups(my previous setup).

Tree Tabs sometimes repeats loading.

Once Turn off "Discard tree structure after browser's restart" option, and turn on to it will be fix.

Very useful; I mainly use it to show my tabs vertically. Lots of options for customization! Also very helpful for restoring a session when Firefox gets shut down unexpectedly (Windows reboots, crashes, etc.)

unfortunately i just lost all ~100 tabs when installing "context seach" addon last (after tree tabs), keeps crashing. all tabs gone. i dont know why.

this addon would be perfect for me if it would not constantly crash the whole system...firefox remains to be unstable
also for wide displays the option to eliminate tabs on top view?

I've switch off automatic tree structure. Nevertheless, sometimes it closes many tabs when I close only one — like they was affilated. It's terrible.

So good ! Thanks ! I am discovering it for now but so much better than competitor. You can configure so many settings ! Try to have a middleclick mouse this is usefull here.
I think im gonna donate cause its realy a productivity enhancer.

I think this extension is the best replacement for Tab Groups.

To make this ideal, I need a keyboard shortcut to cycle groups (Tab Groups had Ctrl + `), and to be able to hide the list of tabs while showing the list of groups, (or have a separate dropdown menu of groups on the toolbar).

But it works well and I've found it more intuitive than alternative extensions. Thanks!

Multi selection with Command+click can not work on MAC OS

Been using Tree Style Tabs for years but found this and decided to give it a whirl. After three days, decided to clean up a mess of tabs. Selected one tab to keep, clicked "Close other tabs," and sure enough ALL other tabs closed. Unfortunately that included ALL my pinned tabs!! MAJOR oversight!!! Uninstalled. I'll stick with Tree Style Tabs. I find it far better designed and better thought out.

Edit for added detail: A few other reasons I've ditched this in favor of TST:

Messed up the order of pinned tabs
Doesn't have a decent way to organized tab groups automatically with good settings
Appearance settings are way to convoluted. Users shouldn't have to be web designers to understand what to do with appearance settings. There ought to be a few graphical examples of choices. Keep it simple stupid. Simplicity is always better.
Honestly, I find the appearance in terms of usability far to cluttered.

In short, IMHO, Tree Style Tabs is so far ahead of this extension in terms of feel, look and usability right out of the box this one just isn't worth the time. Yet...

Fantastic extension.

Vertical tabs in sidebar is so much better than unreadable horizontal tabs. F1 to open the vertical tabs. Only use Folder feature. You can open and close folders and sub-folders to keep the list manageable.

When you close Firefox and then reopen, your vertical tab list reappears. Perfect. No performance hit.

You can get rid of horizontal tab toolbar using userChrome.css. google it.

Dont know what Groups and Sessions are used for.

This extension makes Quantum worthwhile. But I still need a NoScript replacement.