Comment 6 for bug 1551171

I don't know, I don't use gnome, but some gnome libs are installed (Opensuse). But I use apparmor and when I blocked access to /usr/share/applications/mimeinfo.cache in the hope some other way was used, there was not even a default app shown, so I am quite sure it is used by firefox somehow. Besides, before upgrading from 9 to 10 I didn't have a problem with this behavior, it worked ok, although in thunderbird, which is of the same version all the time, it started in 8 or so that I suddenly had chromium as the only option to open url's which at the time I didn't trace back to this problem.

As for finding the default app, wouldn't that be xdg-mime query default ? And if there is a need to use mimeinfo.cache, why not have all apps listed there in the dropdown list so the user can easily select? Now a user has to know which executable he needs to open something, not always easy.