Snap zoom / sound to scene
Two related points:
1. When you create a zoom / pan or add sound, they don't move with the scene in the same relative position if the scene's length is changed, and you have to move them manually and sync them tediously again. would make sense to enable them to move to the same spot in the altered scene.
2. When synching sound or zoom/pan to a scene, it is very hard to hit the exact timing at the beginning or end of the scene. Need a feature of "snap to start / end of scene).
