How about a big fat "Play" button so we could start the song easily. (This would have to be an option as it would take up a lot of screen real-estate. But it would be handy on a gig where you play a slow introduction on a keyboard and then start the song up.)
How about a keyboard shortcut to insert the repeat sign similar to the way the shortcut for inserting a bar line works. This lets us touch typists enter chords fast. Also it would be nice if the arrow keys would let us move over the arrangement rather than a lot of mouse work.