Scribus files open in Firefox if Scribus is not installed, should offer to install it

Thank you for your bug report, could you add an example file to the bug? I guess that the scribus format is a subtype of xml or similar that firefox claims to handle, that's not really a bug...

that problem is not really solvable, the other side of it is "should open a .c file in gedit" or "should be suggest installing an IDE for it"

The document on this page (which I extracted and attached here):
http://www.april.org/poster-le-logiciel-libre-comment-ca-marche

Even after installing scribus-ng I have to manually assign the application.

I am not sure I understand your second comment, .c files do open with gedit if no IDE is installed which is a sensible fallback. Opening a (presumably) known file format in Firefox isn't, OTOH.

> .c files do open with gedit if no IDE is installed which is a sensible fallback.

.c are a known format, they are subtypes of plain text which opens in gedit

> Opening a (presumably) known file format in Firefox isn't, OTOH.

how is that different from the gedit case? firefox claims to handle xml so nautilus use the "best" option it has, since nothing installed claim the specific mimetype for scribus it picks an xml editor, the same way it picks a text editor to display a .c

That's what I am saying, it's the same except we don't have a good fallback. Failing a good fallback, Ubuntu should propose applications/packages known to handle that format, in this case, scribus-ng.

Wow, this is not a recent issue at all:
https://bugs.launchpad.net/ubuntu/+source/scribus/+bug/305114

what is a good fallback and what is a bad fallback? how do you programaticly know that firefox is a bad fallback for scribus files, is it a bad fallback for all xml files? if it is should it still be listed as handling xml?

the bug you point should be fixed with triggers, what mimetype is displayed in nautilus properties?

The issue is a chicken and egg problem. Without scribus installed, nautilus has no knowledge at all of what a scribus file is, so it correctly identifies the file as a standard xml file (as that is basically all it is really), and picks an existing application that handles xml files (and Firefox is more than capable of viewing xml files)

Nautilus now says "Scribus Document (application/vnd.scribus)" - this is after I assigned the file type to it permanently when I first tried to open it unsuccesfully.

Since Scribus is often mentioned as one of the major desktop applications in the Ubuntu official documentation, I was expecting a better user experience for this, much like when I try to open media files in unexpected non-free formats. See:
http://www.ubuntu.com/search/google-appliance/scribus

COuld we use the same mechanism to recognize Scribus files?

one thing we can easily do is move the mimetype definition to shared-mime-info, that should address most of that specific case

This bug was fixed in the package shared-mime-info - 1.0-0ubuntu3

---------------
shared-mime-info (1.0-0ubuntu3) precise; urgency=low

  * debian/patches/scribus.patch: list scribus type so nautilus suggests
    to install the software correctly (lp: #972475)
 -- Sebastien Bacher <email address hidden> Wed, 04 Apr 2012 17:54:05 +0200