Takes up too much screen space, when not working with browser window maximized. Please add a feature to auto-collapse to the left or right when not in use and auto-expand the toolbar while hovering over it only.

Thanks for all the features included so far. Cheers!

this addon has the right idea, but i need to be able to save sessions with ease like "tree tabs" allows me to do. also the way that extension has groups that I can select and hide the rest of the categories of stuff I have open is simply the better way to do things.

It automatically closes parent tabs sometimes, and it is really annoying

Great addon, but not sure why the Plain Dark theme was removed, was a perfect match for my dark browser theme. Had to revert to an older version.

Absolutely brilliant -in theory. However the inability to rebind the F1 hotkey (which I use for terminal dropdown) makes this addon uncollapsible for me.

Firefox v. 73.0.1

I'd love to give this five stars but I have one major problem and one suggestion:

*I've found TST crashes the browser pretty reliably and Firefox can't restore my session. I'm a serial tabber so losing 100-200 tabs that I accumulate over the course of a week or two kind of kills me. The only thing I've found that might be helpful to users/in troubleshooting is that TST crashes far less when only one window is open. I'd say it crashes every 15 min - 2 hr when multiple windows are open but less than once a day if only one window is used. Also, one window only is far less likely to wipe your session.

*Search function: Again, as a serial tabber, I'd love a search function to find a tab quickly. This is especially true since crashes often wipe the session. opening all the tabs again, combined with the nesting feature - I think it'd be very helpful.

THANK YOU for creating this extension. I hope I didn't come off as ungrateful with my criticism. Only trying to help. Cheers!

Très bonne addons mais très gros problèmes de perf

First to say, I would like to give TST 5 stars, but with
a) Missing Search Function (more to that later)
b) Missing Savestate Function (more to that later also)
it cannot have more than three.
Unlike User Coolvibe, I have no problems with TST for more than a year. I have always about 900 - 1000 Tabs open. My OS is Win10 x64 with 16G of RAM, and pagefile is off. After a restart, it takes about 10 seconds to initialize TST icons, but with that much tabs it is ok. I would recommend to anyone who works like me to run process explorer to look at the memory consumption. If it reaches the maximum, which is easy in Firefox by changing between Tabs, FF becomes instable, and Tabs will begin to crash, maybe due to my deactivated pagefile.
I think that FF needs a lot more memory with TST, and maybe user Coolvibe is on Win32, which isn't really suitable anymore for some applications, FF included, because the devs do not care very much. I have on another machine a 32-Bit FF on a 64-Bit Win10, and it isn't as stable as the 64-Bit-FF, so maybe Coolvibes' problems are from there.
To paragraph a)
That is a very arrogant behavior of the TST devs to say on their page THAT REQUESTS FOR A SEARCH FUNCTION ARE IGNORED. Why ? The Opera/Chrome Sidewise has this. I am eager to know why a dev spends dozens of hours for a sophisticated program like TST, and refuses the most useful and simple functionality EVERYONE needs. I know people who are constantly using 2000 - 3000 Tabs and would be VERY HAPPY to have a simple search button. And NOT by installing ANOTHER addon that needs permissions to this and that.
To paragraph b)
A SAVESTATE Function would be very helpful in case of a heavy FF crash (that happens sometimes) or migration. Where tree informations are lost together with all open tabs. I use Tab Session Manager, but sadly, it doesn't save the TST tree informations. At least it didn't the last time, so my restored tree was completely flat, and I had to spend an hour or two to make new indentations (remember, 1000 tabs...).
Conclusion:
TST has a lot of useful functions, it grew from nearly crappy to very stable and relieable during a short period of time, but the focus went off a bit from real usability to functionality overload. I couldn't even find a SIMPLE function to give the active tab a special color. Maybe I'm too dumb or too impatient. But there are even several addons that are extending TST, and they do not fulfill the aforementioned search and savestate functions.

Decent customization, the large lacking feature is the ability to hide all of your tabs up top.

after using this, and accidentally found another add-ons called Sidebery. I think this needs to be developed further, because what is here is in the sidebery and even more features. Don't know why Firefox recommends these add-ons more than Sidebery

UPDATE 3-STARS: Frustrating that a core function to group selected tabs has been removed and now requires a separate extension to be installed.

ORIGINAL 5-STARS: Great extension, love that it can be extended by other extensions too.

Jul 1, 2021 - MANY BUGS:
- frequently crashes and "restarts" add-on and sidebar... I tend to have 500+ tabs open (currently 1600+)

- for some reason sometimes tab tree opens into a new window when I am simply clicking tabs in sidebar.... and I DO NOT even have the "Tree Style Tab in Separate Window" option added

Enhancements needed:
- need to improve the highlighting of which tab is the current active tab.... something like a black border... including when using with Colored Tabs

- need a command to be able to separate 1st tab from tree... instead you have to move all the other sub-tabs

Nov 28, 2019 - please add search function/filter to tabs - I see this was just added as of Jun 2021 - YAY! (looks like still beta version though but nice move!)

Aug 9, 2019 - Please add keyboard shortcut for Mac, preferably one-handed, e.g. OPT-1

Seems when i restart firefox the connection to the parent tab is dropped, so structure end up flat again. A bit annoying, and looses a big part of its function. Otherwise a nice addon with potential.