Thank you for this very useful addon, cannot use browser without it.

Splendid job on converting to Firefox Quantum. With the changes to chrome.css from the wiki, it looks great!

Perfect when opening lots of tabs on a widescreen monitor. All tabs remain readable contrary to the normal tab layout.

if not this plug-in I'd give up using FF and go for Chrome!

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.