public override void PlaylistStateChanged(Playlist aPlaylist, object aUserdata)
            {
                var updateWork = (UpdateWork)aUserdata;

                if (!iPlaylistManager.ApplyChanges(aPlaylist, updateWork))
                {
                    return;
                }
                aPlaylist.RemoveCallbacks(iPlaylistManager.iCallbacks, aUserdata);
                aPlaylist.Release();
            }