Modifing nested sequences
I think for the user interface it would be a huge step forward to represent nested sequences as a group of grouped objects enclosed in a box. In theory my idea would be to create a box that contains all the clips involved in the sequence but keeping them on separate tracks as they were before the nesting. As for the objects external to the sequence on the same tracks of the objects in the sequence I would suggest moving them with an algorithm to the upper track or (if this is not possible) to create ad hoc tracks for the objects. I would keep the idea of double clicking to edit the sequence in another panel, but I would suggest a change to this: once the sequence editing and the return to the main sequence are finished, the panel of the nested sequence closes. For me this improvement would improve efficiency because it would cut the time wasted in finding the right sequence.
Jim Simon commented
I would find that confusing and unhelpful. The current method works best, I think.