No. Try the following code - The ui blocks for 10 seconds - i am sure.

private void button1_Click(object sender, EventArgs e)
{
Thread m_thread = new Thread(new ThreadStart(GenerateTimeLineImage));
m_thread.Start();
m_thread.Join();
}

void GenerateTimeLineImage()
{
Thread.Sleep(10000);
}

I dont think you missed the magic here. I think, you are right that the thread is pointless in this sample. You should speak to the author of this code if hes still in your company.