Back when X1 was first released, I was dismayed to find that I had to hold Shift to constrain note movement in either pitch or time dimensions when using the Smart tool in the PRV.
In previous versions, using the old PRV Draw tool, notes had a time hotspot (the first third of the note duration) and a pitch hotspot (the middle third of the note) where you would get a double-ended arrow cursor indicating that movement would be constrained to one dimension or the other without having to use a modifier key. This was in addition to the note start and end hotspots that we still have.
I submitted a formal Feature Request at the time, but, alas, this was never re-implemented.
I think this time/pitch hotspot functionality could be brought back for both the Smart tool and the Move tool while still allowing the use of Shift to let the note move in whichever direction the user drags first without having to aim for a hotspot.
How about it, Bakers?