I often find myself accidentally queuing up a track, etc. I didn't intend to and sometimes losing my now playing list. I know MB has a pretty extensive history list, but it would be nice leverage this to also allow an "undo" feature for the playlist that would restore the playlist's previous state (which the number of previous states remembered could be customized), or at least some sort of "back" button (maybe this button only shows up in the history list or maybe in now playing's "file" or "play" sub-menu).