The underlying issue is that Firefox (and mozilla in general) does not follow freedesktop's MIME specs.
That is bug https://bugzilla.mozilla.org/show_bug.cgi?id=296443 (Whether Firefox should use exactly the same dialog is of lesser importance: the important part is that the applications listed are the same as for GNOME and KDE applications). You can maybe workaround the issue by going to your profile in ~/.mozilla/firefox/ and locating the file mimeTypes.rdf, then rename it as "backup.mimeTypes.rdf". Restart Firefox and try. If it doesn't work or breaks something else, you just need to rename the file back to its original name. -- Firefox suggests opening PNG with itself, but the gnome default is EOG https://launchpad.net/bugs/42326 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
