go to /home/<user>/.local/share/applications folder and create this
file:

cat > gnome-commander.desktop

[Desktop Entry]
Encoding=UTF-8
Name=application
MimeType=application/x-executable;
Exec=%f
Type=Application
Terminal=false
NoDisplay=true

then gedit /home/<user>/.local/share/applications/mimeinfo.cache
and add this line:

application/x-executable=gnome-commander.desktop

and thats all!