Comment 3 for bug 727325

I managed to debug this by running this from within the dbusmenu branch above.

killall unity-panel-service ; LD_PRELOAD=libdbusmenu-gtk/.libs/libdbusmenu-gtk.so /usr/lib/unity/unity-panel-service

I then checked the Layout within dfeet and it returned this relevant info about the playlist items.
It seems as if the playlist icon name is correct.

 (4,
    {u'children-display': u'submenu',
     u'label': u'Choose Playlist',
     u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee'},
    [(22,
      {u'icon-name': u'source-smart-playlist',
       u'label': u'Favourites',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/SmartPlaylistSource5'},
      []),
     (23,
      {u'icon-name': u'source-smart-playlist',
       u'label': u'Favourites',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/SmartPlaylistSource1'},
      []),
     (24,
      {u'icon-name': u'source-playlist',
       u'label': u'New Playlist',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/PlaylistSource7'},
      []),
     (25,
      {u'icon-name': u'source-playlist',
       u'label': u'Play Queue',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/PlayQueueSource1'},
      []),
     (26,
      {u'icon-name': u'source-smart-playlist',
       u'label': u'Recent Favourites',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/SmartPlaylistSource2'},
      []),
     (27,
      {u'icon-name': u'source-smart-playlist',
       u'label': u'Recently Added',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/SmartPlaylistSource3'},
      []),
     (28,
      {u'icon-name': u'source-smart-playlist',
       u'label': u'Unheard',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/SmartPlaylistSource4'},
      []),
     (29,
      {u'icon-name': u'source-smart-playlist',
       u'label': u'Unwatched',
       u'x-canonical-sound-menu-player-playlist-path': u'/org/bansheeproject/Banshee/Playlists/SmartPlaylistSource6'},
      [])]),
   (16, {u'type': u'separator'}, []),