C#

private void button2_Click(object sender, EventArgs e)
{
   demothread = new Thread(new ThreadStart(ProgSafe));
   demothread.Start();
}

private void ProgSafe()
{
   for (int i = 0; i < 100; i++)
   {
      Thread.Sleep(200);
      if (this.progressBar1.InvokeRequired)
         this.Invoke(new SetProgCall(IncreaseProgress));
      else
         IncreaseProgress();
   }
}

private void IncreaseProgress()
{
   this.progressBar1.Value += 1;
}