Scenari is based on XULRunner too.

* https://scenari.software/en/ * Repository: https://source.scenari.software/projects/dev-core/repository

There were also, among others:

- InstantBird, a multi network instant messenger client

- Celtx, a media prepoduction software

- Boxee, a HTPC app

- Kiwix, an offline Wikipedia reader

Many of these either vanished or transitioned to something else (I think both Komodo and Celtx did).

And songbird, a media player.

> Many of these either vanished or transitioned to something else (I think both Komodo and Celtx did).

I know Celtx decided to drop the concept of desktop app altogether and went full web-based-only SaaS.

The desktop Celtx app was a good screenwriting program that was easily affordable for hobbyists and the pivot to a paid subscription service with less focus on just screenwriting and more focus on other preproduction activities left a small hole for a short while. (These days the Fountain ecosystem seems the best suggestion for the hobbyest screenwriter.)

There was also Miro which was a pretty neat media player with RSS Torrent support

- http://www.getmiro.com/

The Palemoon browser [0] also still uses XUL, and is in many ways a continuation of XUL browsers (was originally forked from FF 29, updated with various components from FF 50+, and with many other tweaks).

[0] https://palemoon.org

There was also instantbird - an IM client that let you connect to various IM platforms (MSN, AIM, Yahoo!, Facebook before “Messenger”)

https://en.m.wikipedia.org/wiki/Instantbird