What’s the idea?
Similar to how you can select note length, or clip chains, etc. Select the start point and end point of a speed zone. A speed zone would apply a time multiplier/division to those steps only. Additionally, it would be great if it could also be set for a single step as param lock. For example, the sequence runs at x1 and at a given step it slows down to /8 for a single step and then goes back to x1.
