Allegedly, on or about 29 November 2016, Stuart McGraw sent:
How can I tell my desktop (fedora-23/xfce4) to use Emacs to open any file with a ".org" extension? Everything I've found on the internet seems to set an application based on mimetype but ".org" files are seen as "text/plain" (at least by the 'file' program) and I don't want to open all text files with Emacs, just ".org" ones. Thanks...
I suppose that really depends on how you're opening them. If your filemanager handles your desktop, it may be configurable to that degree. Some of them seem to care more about the extension than the description, or at least treat extensions as individually configurable sub-divisions. Though it may be possible to create an extra mimetype just for those files (e.g. call it text/something-else).
If you're talking about files coming straight from a web browser or email client, then the supplied (not your own) mimetype description may well take priority.
What do you get as right-click options for such files? Is there an open-with type of thing, or a properties box that lets you set up your .org files with their own special defaults?