Behavior of playlists under newest archive version (r30258)

[pwabrahams]

The archive version of Rockbox for the Sansa Clip+ seems to have much improved playlist handling, but its behavior is still mysterious.  If I start from the main menu and go to Playlist Catalog, then select a playlist, I see a list of tracks in that playlist.  So far so good.  But how do I actually start one of them playing?  I've tried Select, Long Select, and Right.  None of them do it.  What might be relevant is that I already have an active playlist, but if so, how would I get past that to start using a different playlist?