[Nautilus-list] Open with Other -- how does this work, anyway?

[David Moles <david moles vykor com>]

Hey, this probably isn't entirely a Nautilus problem, but I'm
not sure what to do with it. I have a new document type (LyX
documents) and I want to associate it with an application 
(LyX)... also I'd like to give it an icon.

Unfortunately, (1) Nautilus recognizes .lyx files as plain
text documents -- I presume because so does file(1) -- and (2)
since I upgraded to control-center-1.5.9-ximian.1 it's no longer
possible (as far as I can tell) to "configure which programs are
offered for which file types in the GNOME Control Center". (You'd
think this is what "Default Applications" would be, but it isn't.)

I know I should take (2) up with Ximian or somebody (and if 
anyone can tell me the right forum to do that in, I'll be happy
to) -- but (1) seems to be a symptom of a messier problem -- the
whole file types, MIME types business seems to be both screwed
up and poorly documented. For instance, LyX files are easily
identified by either their extension or by the fact that they
start with the string "#LyX", but I have no idea how to inform
Nautilus (or any other part of the system) about that. Earlier,
I ran into the problem that StarOffice 6.0b .sxw files just look
like a ZIP archive to Nautilus -- and the same problem, I assume,
will arise with any other file format that uses ZIP or gzip or
tar+gzip as the last action in its save chain...

Anyway, for LyX and file(1), I suppose I can hack /usr/share/magic, 
but Joe Home User is going to want a better way. And what about mime
types? I know there's /etc/mailcap, but I also see I have files
in .gnome/mime-info that say "this file was autogenerated by
gnome-vfs-mime-info, DO NOT EDIT". I'm tempted, though, since
neither gnome-vfs nor gnome-vfs-extras seems to have any executable
files associated with it. Any ideas?

--D