Please follow the instructions at:
http://cgit.freedesktop.org/xdg/shared-mime-info/tree/HACKING#n31
for mime-type additions.

Created attachment 67246 [details] [review]
patch

Matthias, does application/x-gtk-builder seem ok to you?

sure, sounds fine to me

The test suite fails with your value in tests/list:
gtk-builder.ui, 'name' test: expected application/x-gtk-builder, got application/x-designer

Committed with that fixed.

commit 77c334309bba791eb7f0c8e4cd0f9053502fd27c
Author: William Jon McCann <jmccann@redhat.com>
Date:   Sun Sep 16 11:30:02 2012 -0400

    Add application/x-gtk-builder type
    
    https://bugs.freedesktop.org/show_bug.cgi?id=28020

Any reason to not go with the application/x-glade mime type we've been
using forever ?

Won't this cause some conflicts, like:
   https://bugzilla.gnome.org/show_bug.cgi?id=698705 ?

I don't really know all the details of how mime types work,
just asking out of curiousity, as it seems to have broken
something (at least in anjuta) to have invented a new mime type.

I think a new Mime type is justified because these are two different file formats - albeit both XML based with a .ui extension. It would be perfectly reasonable for an application to be able to handle one format but not the other, in which case it would just list one MIME type.

For reference, here are samples of glade XML (the old format):
http://people.gnome.org/~newren/tutorials/developing-with-gnome/html/apb.html

And gtkbuilder XML (the new format):
http://www.pygtk.org/docs/pygtk/class-gtkbuilder.html#gtkbuilder-ui-definition-example