Try these: https://addons.mozilla.org/en-US/firefox/collections/mozilla/tab-organizers/

all these poor alternatives have only a little part of the wunderful functions of tabmix plus. tabmix plus was a top-ten addon. Why had nobody a look at these inherent functions?

And again the tabs on the very top, this is ineffective and effects much more extrinsic load / ballast. Why are they doing such stupid things? Is there nobody with a minimum level of usability-skills? firefox has become worse for me, want the old version back :(

Firefox's style or appearance can be modified by creating a chrome folder inside your Firefox profile folder and then placing a userChrome.css file inside, that includes a custom style rule. The rules you put in the userChrome.css file will override the default styles in Firefox.

Note: Custom style rules might not work every time because of other factors (such as incompatibility with other custom style rules) beyond the Mozilla community's control. Your custom style rule might also stop working each time a new Firefox release comes out.

Here's how to modify Firefox so that tabs are shown below the address (URL) bar instead of at the top:

If your Firefox profile folder already has a chrome folder containing userChrome.css:
Go to https://www.userchrome.org/what-is-userchrome-css.html and copy the CSS rules under the "Move the Tab Bar Below the Other Toolbars" example here into your userChrome.css file. After saving your changes and closing the file, you should turn on your Firefox title bar or menu bar on Windows. (The CSS rules you copied include other suggestions as comments.)

Otherwise, follow these instructions:
(See this help page and our community member's video starting at 8:45 for more information.)

1. Open your currently active profile folder: Type about:support in the Firefox address bar and, under the "Application Basics" section next to "Profile Folder", click Open Folder (Windows) Open Directory (Linux) or Show in Finder (Mac).
   • On Mac, a folder will open that contains your profile folder. Open the selected profile folder (it will be named something like xxxxxxxx.default for a default profile).
2. Create a new folder named chrome inside the profile folder.
   • Create a desktop shortcut to the chrome folder, if you wish, for easier future access.
3. Download and save this file, then move it into that chrome folder:
   https://www.userchrome.org/samples/userChrome-tabs_on_bottom.css
4. Rename the file from "userChrome-tabs_on_bottom.css" to userChrome.css
   • On Windows: If the file you saved was named "userChrome-tabs_on_bottom" (the .css was missing), rename the file userChrome instead (see the note below).
5. Restart Firefox, which will discover the new userChrome file and apply the rules.

Tip: Turn on your title bar, or the menu bar on Windows, after you've made these changes.

Note for Windows users:
On Windows, file name extensions are hidden by default. If the file you downloaded was saved as "userChrome-tabs_on_bottom" without the .css extension, that means Windows is hiding file name extensions. In that case, you must rename the file userChrome so that you don't end up with a file named "userChrome.css.css" that won't work. To set Windows to show file name extensions, see this Microsoft article for Windows 7. See these fileinfo.com articles for Windows 8 and Windows 10.

thanks, MkII (Deep Purple?)

if i want to become programmer somewhere along the line, i definitely will use this helpful information. As a normal user however the procedure is too far away from things like "usability". Why ist mozilla doing such thinks? I don´t understand this. Why do they working things worse? :(

Here is why it was needed to be done: https://www.howtogeek.com/333230/why-firefox-had-to-kill-your-favorite-extension/

Hi @dHann. I have been a long time Tab Mix Plus user and understand your frustration. @Mkll has given you some excellent advice on things that can help - I use a userChrome.css file myself, although for slightly different mods (including bringing back yellow bookmark folders, rounded tabs and hiding recently bookmarked, etc.).

The reason that I am posting is that the good news is that a web extension version of Tab Mix Plus is being worked on. See here:

http://tabmixplus.org/support/trouble.../legacy-tabmix.html

There is also a forum thread about the web extension features people would like to prioritize (or help with) here:

http://tabmixplus.org/forum/viewtopic.php?f=1&t=19932

I thought that this might help others who see this thread, as well as yourself. Hopefully, enough people will support the main developer in various ways for it to happen.

thanks @both