Out of curiosity, what happens if I held down more then two keys in mono mode?
Keep in mind that only 2 notes are in memory. The Base note, and the last note it was gliding to.
So here is how it works :
1 . The first key your press is the based note (A)
2 . Then you press and hold other notes (B, C, D). It will glide to B, then C then D. The base note will remain A untill it's released.
From this point A,B,C,D are hold down but B and C are not in memory anymore, so B and C don't have any impact on future actions:
3.1. If you release D, it will glide back to A .
3.2. If you release A, the base note will become D. So D will become the return note of future notes until it's releaed.
3.3. If you release A and D the sound stop (although B & D are still pressed).
3.3 is not ideal, but it's a corner case to my opinion.