When in MC and pressing F4 it will open an editor looking the same as when you press F3.
F3 is only for previewing files.

However now when you press F4, it will open something looking like VI.

More info here: 10.10 - How to switch the editor in mc (midnight commander) from nano to mcedit? - Ask Ubuntu
Unfortunately this does not work with the MC coming with the 2-22 version :frowning: