I don’t get you… fold is best than just highlight, it show you the specific scale you are working on, avoiding the rest of the notes…
Im not sure Ive understand your question, but fold is per MIDI track, works individually, if you have only 6 notes of the scale then you will see only those 6 notes, that chord you see at the left in the image, is out of the grid (I added by myself) and you can add or delete the notes you want to keep only the ones you need… if you want to add more, you can click the fold button at the left to unfold (I mean in Ableton) and you can see the normal piano midi editor, you can fold and unfold instantaneously, this is not a complex process is just a option/view in the editor
I guess with 6 notes you mean this?
4 notes
3 notes without a chord helper at the left
this is also helpful when working with a drum pad like groove agent, I can say is also a comfortable view helper