Drop zones get bigger when highlighted. This moves things around and so is annoying.
Some drop zones don't fill the available space. In particular at the top level sequence, the final drop zone should expand to fill all the space below it. However this has to play nicely with scrolling. Until the area is filled, it should expand to fill the whole area. Then once the sequence's visual representation fills the whole vertical space, the drop zone should just be regular size.
Drop zones get bigger when highlighted. This moves things around and so is annoying.
Some drop zones don't fill the available space. In particular at the top level sequence, the final drop zone should expand to fill all the space below it. However this has to play nicely with scrolling. Until the area is filled, it should expand to fill the whole area. Then once the sequence's visual representation fills the whole vertical space, the drop zone should just be regular size.