Problem with FireFox Quantum.
It is not possible to display two panels, left and right at the same time.
In the previous version firefox (56.*) it was possible to display bookmarks in the left panel and on the right opened tabs at the same time.
Now, in FireFox Quantum, only one panel is available, left or right at one time. Open tabs are displayed at the top and do not depend on whether the Tree tab is enabled or not.

exactly what I need!! since years indispensable for any desktop web junkie who wants to use more than 10 tabs...

It's awesome. My wide-screen monitor is finally useful.

Very customiziable and does exactly what I been looking for.

Words cannot express how awesome this plugin is (and has always been). I have been a TST user for many many years and it is the first extension I install on FF on any computer I use and is also the only extension for me that counts as a must have. It makes my browsing experience so much more richer and I am eternally grateful to the author for his continued hard work on this extensions (especially to port it to the latest FF which was no small undertaking).

Works great, helps me keep my tabs organized better than any other tab extension out there.

If you are trying to remove the tabs from the top, please try the code at my gist: https://gist.github.com/SgtPooki/3e4143de258563653fc4082b2ac0f886

Install this extension now.
Press F1 to toggle the tab sidebar - tabs are a "child" of the tab you opened a tab from. This means your tabs are auto-categorised and you can see the "history" of how you got to a page at a glance.

I was concerned this would no longer be available for FF57, but the author has re-written the extension, leaving it better than ever.

It fits new firefox design :D

I've been using TST for ages now. I'm glad to see it's made the leap to Firefox 57, and it works really well here. Highly recommended!

An essential extension for those who open a lot of tabs. It is especially useful for grouping tabs from various sites.

It would really be helpful if it were possible to disable the tabs at the top of the page.

Well designed, simple, and easy to use. Beautifully integrated into the builtin Sidebars. Tabs are automatically arranged in a hierarchical structure and you can fold and unfold a parent item. I've only started using this minutes ago, but I already love this addon!

great, but now i have tree tab, the orignal tab bar is not nececery now, how can i make it disapear?

Very useful, clean and light weight. Also, an excellent port to the new firefox infrastructure.