By that i mean by key/mode. Selecting A minor for example from a little dropdown list would hide all piano keys except those in A Minor. Same could apply to modes. I think it’s Ableton’s that’s got something similar but Steinberg could do it better. 
Yes please Steinberg I would love this feature!!
I’d like if if we could hide keys witout data on them. Customizable with top and bottom boundaries to hide and reduce the range of the roll. Sometimes editing a few notes in a 10 octaves range is a pain. Why would I need a 10 octaves roll on a triangle patch or a piccolo patch.
Please steinberg, let us cutomize our midi editors.
+1 I would gladly pay for such an upgrade. It would pay for itself in my workflow.