Yeah, the flag doesn't affect userChrome.css or userChrome.js at all (I've tried it every which way and even reset it (cleared the value) just to make sure).
It looks like the instructions there are incomplete so I got the JS at the second link to work only by accident by adding and deleting other files before I added the bottombar JS: you need that and the CSS they give you, but you also need an XML file found here: https://github.com/nuchi/firefox-quantum-userchromejs(and you might also need the userChrome.js file found there, but until I can clear Fx script cache a few more times, I won't know for sure!)edit: you don't need it, actually, just the JS, CSS and XML files mentioned are needed.
Turns out AutoConfig and userChrome.css can control very similar things so maybe that's why people get them mixed up: https://www.userchrome.org/what-is-userchrome-js.html. As far as I can tell one seems to have no dependency on the other, while AutoConfig can do things like set browser preferences that I'm thinking userChrome can't.
Re: Mozilla/Firefox did it again
The JS and CSS in the first link in your top post didn't work, but for some reason this identical JS did (I've done a line-by-line comparison and can't find any errors in the first. I could run an actual diff but don't _think_ I have to?): https://www.reddit.com/r/firefox/comments/8kxpbc/is_there_any_extension_that_can_create_a_status/dzbzw9v/ (parent: https://www.reddit.com/r/firefox/comments/8kxpbc/is_there_any_extension_that_can_create_a_status/) Edit: ran a diff but it just brought up spacing and comment variations that shouldn't affect the result.
It looks like the instructions there are incomplete so I got the JS at the second link to work only by accident by adding and deleting other files before I added the bottombar JS: you need that and the CSS they give you, but you also need an XML file found here: https://github.com/nuchi/firefox-quantum-userchromejs
(and you might also need the userChrome.js file found there, but until I can clear Fx script cache a few more times, I won't know for sure!)edit: you don't need it, actually, just the JS, CSS and XML files mentioned are needed.Screen cap, with a few add-on icons dragged over for demo purposes: https://intoolate.files.wordpress.com/2018/09/bottombar.png
Turns out AutoConfig and userChrome.css can control very similar things so maybe that's why people get them mixed up: https://www.userchrome.org/what-is-userchrome-js.html. As far as I can tell one seems to have no dependency on the other, while AutoConfig can do things like set browser preferences that I'm thinking userChrome can't.