• Firefox offers better privacy and security than Chrome, with upcoming support for 200 new add-ons. • While Chrome dominates, Firefox gains ground with user-friendly browsing experience and open-source model. • Mozilla’s focus on user privacy and transparency challenges Google’s ad-centric approach, making Firefox a viable alternative.
If I remember correctly, XUL/XBL is dead. They removed that code a while back after they transitioned to WebExtensions. The current frontend is HTML, CSS and JavaScript.
There are still bits of XUL around but I believe the preference is to use HTML elements wherever possible and they’ve been stripping elements out.