Try the following
On my computer, this is what I see when I search for gedit.desktop
If I search for nautilus.desktop (under GNOME)
See if this helps.
---------- Post added at 09:07 AM ---------- Previous post was at 09:07 AM ----------
There could be a easier way out of this. But, I have changed file type associations in the past this way (I like editing configuration files ... )