"The XULRunner 1.8.0.x series of releases are stable developer previews. They are based on the same gecko branch code as the Firefox 1.5.0.x series and they will contain all the security and stability fixes from that codebase. However, they do not contain all of the functionality that is planned for the final XULRunner releases, including code to manage application installation, uninstallation, and upgrade." (from
http://wiki.mozilla.org/XULRunner:Roadmap)
Last time I checked "stable developer previews" didn't mean "Ready for wider use", but Firefox is. By release in my last post I meant "end-user-stable" release.
With other words: XULRunner is currently nearly the same as the things you find in Firefox (at least gecko-wise and that is what the depending packages needs).
And since Firefox is something that is "production-enviroment-ready", and XULRunner is not then guess the choice from a distro-view. If you read the roadmap it seems like the first one is not planned before the release of XULRunner 1.8.1 planned for the release of Firefox-2.0.
And by the way: the dependency chart you showed us for Gnome is for dev-2.17, the not the stable 2.16.