Replay Map Construction

It would be awesome to have the ability to replay the construction of a map. Starting from the initial terrain, there could be some sort of Next/Back button you could use to watch the additions/adjustments happen as the map is built. This information is likely stored in the Undo/Redo buffer now, but it gets lost between map loads. Persisting this data and letting people see it would be an invaluable tool for learning authoring techniques.