void back_worker_DoWork(object sender, DoWorkEventArgs e)
 {
     ToggleProgressBar("Loading...");
     plentry   = ViewModelPlaylist.playlistentry.ElementAt((int)e.Argument);
     viewmodel = new ViewModelTracklist(plentry);
     while (!viewmodel.completed)
     {
         System.Threading.Thread.Sleep(3000);
     }
 }
 void back_worker_DoWork(object sender, DoWorkEventArgs e)
 {
     ToggleProgressBar("Loading...");
     plentry = ViewModelPlaylist.playlistentry.ElementAt((int)e.Argument);
     viewmodel = new ViewModelTracklist(plentry);
     while (!viewmodel.completed)
     {
         System.Threading.Thread.Sleep(3000);
     }
 }