I've found something else now.

Even though in the DOM Inspector I see this node
/html/head/script
and it shows the src attribute = /images/jscripts.js

when I was sniffing the network, I see that Mozilla does not make a request for this file.

This is why the javascript pretty much doesn't work in Mozilla when viewing the stylesheet applied XML.

Now, to find out why, and how to workaround it.

Chris