Isn't /usr/bin/htmlview the script which one is supposed to call (it does some
gconf magic I can't follow easily iff gnome is running) or am I confused more
than usual...

We just set (the default) network.protocol-handler.app.{http,https,ftp} prefs
to "/usr/bin/htmlview" in a hack we load after thunderbird, and it seems to
work (from my limuted testing anyway and no complaints from users yet).

Of course our default browser is still mozilla and we hack /etc/htmlview.conf
to point at that (the user can still override it of course it is just a default
if they havn't set an htmlview value (or used gconf to set a preferred browser)...

Or maybe I've got the wrong end of the stick here...

 -- Jon