It's used for things like pop-up menus, (i.e. things that can't be done with HTML) and was recently used in some obscure parts of the UI e.g. certificate viewer (however I'm not even sure that's still XUL any more)

I think it's safer to say: It's almost all HTML these days. XUL is very much deprecated.

As we killed XBL, our XUL components because web components. https://briangrinstead.com/blog/firefox-webcomponents/

It’s a mixture of XUL and HTML nowadays. The reason is, most of the things that were only available in XUL are now possible in HTML, and it’s eaaier to find developers who know HTML.

> and it’s eaaier to find developers who know HTML

Rather: find developers who have a shallow knowledge of HTML.

I do claim that it takes much less time as a developer to get to a decent level of XUL knowledge than to get to a decent devel of HTML knowledge.

I agree, but also it’s the fact that there’s a steady supply of devs who already know decent HTML, while not many who know XUL. It would be easy to apply your HTML knowledge to XUL, but since we already support interleaving HTML and XUL, why not let people just use what they’re used to?

That said, I didn’t really look into it all that much! I just happen to know about it because I was doing some userChrome.css stuff back in the day.

Just came across this Firefox.html announcement in another thread and it might have some more context: https://web.archive.org/web/20230402033035/https://mail.mozi...