I have settled Reaper to open the midi editor with
ONE click.
I don't know if it is by design, but if I want to see the midi notes, I have to click twice on the midi item! Why when we click one time, we can't see any notes (no scroll midi editor window)?
Mouse modifier: Media item/
left click --> Item: Open in built-in MIDI editor (set beahavior in preferences)
One MIDI editor per track. Open all midi on the Same track.