All Browsers besides FF uses tabs nowdays and if those Addons aren't update to support the lastest FF or other Browsers update then you will have to live with tabs. What is the actual problems with tabs? I use and many other uses them and some sites opens tabs opens tabs by themselves that is not something you can control. Tabs are not inconvenient nor confusing. If your opening to many of them then you need to only open those needed and there is another option you can open Multiple separate Browsers of FF instances but then your asking for trouble there as well.

rj180 said

Tabkiller solved the problem but you stopped supporting it.

The developer didn't migrate the add-on to Webextensions - hadn't even updated since 2007 ......

How do I permanently diable tabbed browsing?

This will not disable tabbed browsing, but it might come close to what you want :

https://addons.mozilla.org/en-US/firefox/addon/no-tabs/

Worth a try ......

Tabkiller lives! Sort of. I wrote a replacement for the old extension, as there were at least 3 people who expressed interest. Perhaps it will work for you:

https://addons.mozilla.org/firefox/addon/i-hate-tabs-sdi-for-firefox/

Edit: I wasn't aware of No Tabs, which uses the same approach of watching for new tabs and moving them to new windows. I think the main difference is I have code to ensure that tabs in private windows move to private windows, and to maintain full screen.

I would definately give jscher2000's extension a try  !

https://addons.mozilla.org/en-US/firefox/addon/i-hate-tabs-sdi-for-firefox/