This is must have extension. It would be even greater if it could work in tandem with ColorfulTabs.

Just to remind older comments. One can hide FireFox tab bar and Side Panel title with userChrome.css file like that:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

/* to hide the native tabs */
#TabsToolbar { visibility: collapse; }

/* to hide the sidebar header */
#sidebar-header { visibility: collapse; }

The best vertical tabs solution. I cannot use Firefox without it.

After Firefox killed TabMixPlus I thought I would have to switch to another browser. Eventually I found Tree Style Tab, which is even better. Now I just wish I had a way to turn off Firefox's own tabs, since they are so lacking in features as to be almost useless.

Pretty happy with this after doing some of the "Advanced" style customizations that the author suggests on the wiki. This is a much better tree-tab experience than anything I was ever able to achieve with Chrome (Sidewise is the best I found there).

Dear Piro,
Thank you for making something that works with Firefox 57! I know you're doing the best you can with the limitations, and thank you for the helpful information on the Wiki!

Tab Tree no longer works - so switched to this.

I think I like it better.

You can open tabs in categories, you can collapse a tree and close all the children tabs with one-click.

Well done devs updating for 57! A quantum improvement.

MERCI for having ported Tree Style Tab to FF Quantum !!
Don't know how to do without it
Indispensable addon for Firefox :)

I grudgingly migrated to Tree Style Tab after the tab groups extension became incompatible. Now I cannot live without Tree Style Tab! It makes everything way easier to see and manage. It helps closing old tabs and finding the one I want. This is one of my favorite extensions ever.

Some people have a strange way of thanking Piro for updating the addon in time for Quantum and allowing users a transition as smooth as possible. He even found the time to document all the things that just aren't possible yet with the new webextension API, like hiding the original tab bar. With a quick look at the extension's github pages you also find solutions for that (hint: you have to place some lines in userChrome.css as this is the only way Firefox left to modify the GUI). I'm sure Piro will re-add all these missing features as soon as Firefox development will allow it.

So, from my point of view: this extension is still great and really adding value to the browser. I can live with some glitches and missing features as long as I don't have to cope with the standard tab bar. Instead of whining about things missing, what about contributing some userChrome.css snippets to relevant issues in the bug tracker (you people did report problems there before leaving one-star reviews here, did you?) so that others can participate?

BTW: Is it just me or doesn't a donate button exist? I would love to spare a few dimes for motivation.

just amazing, it helps me a lot with my work

Great Addon, incredibly useful when doing research.
Thanks Prio for redoing the Addon for the new API!

@everyone who is complaining about the lost features:
seriously, it's not the addon dev's fault they changed the addon API. stop giving bad reviews!