Following the message of XenGeek
I used this code to remove Tabs keeping the title bar.

/* Remove horizontal tabs */
#tabbrowser-tabs {
visibility: hidden;
margin-top: 40px;
margin-bottom: -50px;
}

/* Remove sidebar header */
#sidebar-header {
visibility: collapse;
}

Anyway this add-on is very good, I don't understand why this tree tab menu is not a standard in Firefox. Saved me a lot of time and energy !

Thanks a lot !

Extension is very handy. But last update asks for accessing all my web data. Why??? I'm not installing it for now cause there is no justification anywhere why this permission has been requested.

To add on to Anonymous user fc7bf5's comment. If you want to get rid of the Horizontal Tabs and the Title Bar for the sidebar simply add the following in your Firefox Profile. This is not the Local AppData one, but the Roaming one which is normally found at: %UserProfile%\Appdata\Roaming\Mozilla\Firefox\Profiles

You will have a profile folder here, maybe more if you utilize multiple profiles in Firefox. Once you pin-point yours you simply need to add a new folder called "Chrome" in your profile folder and create a new text file "userChrome.css" make sure it is a css file and not a txt. you may have to google how to change file extensions by revealing them in Windows. The contents of that file should contain one or both of the following segments depending on what you want.

/* Contributed by Anonymous user 099626's */
/* Remove horizontal tabs */
#tabbrowser-tabs {
visibility: collapse;
}

/* Remove sidebar header */
#sidebar-header {
visibility: collapse;
}

Once this is done you will have to restart FireFox. Depending on your theme in FireFox you may notice you can't see the windows control buttons in the upper right. To fix this simply go to the "Customize..." menu and check the "Title Bar" option then click done.

ps. I've noticed some FireFox menu's don't take the removal of the Horizontal Tabs into account due to it not being a build in option. With this in mind option screens like "Customize..." may take over your full screen including the TreeStyle Tabs. If this happens simply look for another way to close the screen, which should be provided.

pps. TreeStyle Tabs is a fantastic app that I've used for years, I've slowly started moving to Chrome because of the noticeable speed difference and the large amount of multitasking I have to do daily. I am excited to see if FireFox Quantum can live up to the speed it boasts. That being said...

Happy Tab Hoarding! :D

Tried to make the new version work with 57, but it doesn't. Reverted to 56.02 to resume using the old add-on, which does work.

Why is Mozilla killing off its add-on ecosystem?

It works! And it's a tree! And there are many and sensible config options! And it integrates with containers!! Wooohooo!!!

You have to manually disable the horizontal tabbar at this moment. This is a limitation of the webextension api, not something this extension can currently do something about. But once that's possible, it'll get the final star ;-)

Kein Ersatz für Tab Mix Plus aber wenigstens läuft es im neuen Firefox 57 (Quantum)

Why are so much permission required lately? It's asking right now for every data everywhere and it's kind of freaking me out..
I find this extension very usefull thought

Love the extension. Please find a way to remove the tab bar at the top!

Thanks to Anonymous user fc7bf5 for fixing the problem to remove the tab bar at the top!

With this fix 5 stars. Strange that the creator of this usefull extension didn't solve this problem.

Works well. Just need the top bar of tabs to be hidden.

For anyone having trouble with the horizontal tabs not hiding, Anonymous user 099626's advice worked for me. Create a folder chrome/ in your firefox profile and then in that directory a userChrome.css file containing the following rules

/* Remove horizontal tabs */
#tabbrowser-tabs {
visibility: collapse;
}

If you want to get rid of the sidebar header, add this to the file:

/* Remove sidebar header */
#sidebar-header {
visibility: collapse;
}

You will have to restart Firefox to enact the changes.

Cannot remove tab bar on top anymore.

just got it

Как скрыть вкладки сверху?

Latest update today with the desire for new permissions has caused the addon to fail. Before this I am grateful it was ported over to the new design. This is the main reason I use FF. Please help fix this issue.

Update, just clicked to add again to Firefox and it fixed it. Odd but ieast it is working again.

Best extension ever that keep me using Firefox

Please justify in the description why the permission to access data from websites is required. It could deter people from using your fantastic extension, which would be a shame.

For those interested, justification for website data access permission is given here : https://github.com/piroor/treestyletab/issues/1536#issuecomment-344541809

Requires access to ALL data from websites, read and modify bookmarks, and use notifications... I cannot remotely see why those permissions could be possibly needed...

Requires access to ALL data from websites! I think I'll pass thanks

Must have дополнение для ФФ. Пользуюсь уже много лет.

my only issue (after finding the work abouts for the top bar to go away...is making the tabs "thinner". the one bit of code that was here scrunched it all up and i couldn't make hide nor hair out of my tabs. I suppose screwing around with css and figuring it out is going to be something i'm going to have to do...if only to figure out which tag needs changed to get them thinner without everything running together.