Is it possible to add [multibar="true"] attribute to #TabsToolbar?

[black7375]

I am the author of Lepton(firefox ui fix) and has an issue that wants to support paxmod. black7375/Firefox-UI-Fix#500

This project is webextension, but it seems to be able to load CSS dynamically to the browser ui, unlike general webextentions.
(I don't know how much experiment_apis's limit is.)

Then, is it possible to add attribute to the browser UI?
If you add [multibar="true"] to #TabsToolbar, the multi-row feature is immediately compatible.

Alternatively, about:config pref(Ex. userChrome.paxmode.enabled) is automatically added when installing, but I think there will be difficulties in general webextenstions.

If the above two questions are possible, it will be automatically compatible when installing paxmod.
If it is impossible, the user should manually adjust the about:config pref.

[surapunoyousei]

I have worked on adding this feature. I would appreciate it if you could merge the PR.

Enable:

Disable:

I'm a student and don't have time, so I apologize for the delay in writing the patch.