private void premierStart_click(object sender, RoutedEventArgs e) { if (threads.Count() < 5) { ThreadWorker premierworker = new PremierWorker(nbPremierThread); Thread premierThread = new Thread(new ThreadStart(premierworker.work)); threads.Add(new MyThread(premierThread, premierworker)); premierThread.Start(); nbPremierThread++; updateTextblockDispatcher(); } else { System.Windows.MessageBox.Show("Already 5 threads have been created"); } }