WPF: Basic Thread

using System.Windows.Threading;
using System.Threading;

private void btnPlay01_Click(object sender, RoutedEventArgs e)
{
    ThreadStart start1 = new ThreadStart(Thread1);
    Thread t1 = new Thread(start1);
    t1.Start();
}

public void Thread1()
{
    int x = 0;
    do
    {
      x++;
      Thread.Sleep(100);
      Dispatcher.Invoke(DispatcherPriority.Send, new Action(delegate
      {
        lbl01.Content = String.Format("Thread 1 running: {0}", x);
      }));
    }while (x < 50);
}