I wanted to use geany as my default editor and so i set Default Applications -> File to geany. from then on, everything everywhere (gnomes nautilus, efm, terminology) used geany for any mimetype effectively disabling mime detection.
i don't even know what this is actually setting, i havn't found anything in ~/.local/share/applications/default.list nor any mimetype.list
Also, it cannot be removed/set to null by e's gui. at the end i had to resolve to remove geany, go back to enlightenments gui Default Applications and press apply once.
nightmare, this option should be removed.