winform中在事件中使用线程打开窗口的问题？

Question

private void button1_Click(object sender, System.EventArgs e)
{
  Form2 f2=new Form2();
  f2.MdiParent=this;
  System.Threading.Thread x1 = new Thread(new ThreadStart(f2.Show));
  Thread.Sleep(20);
                     x1.Start();
           MessageBox.Show(x1.ThreadState.ToString());//提示说unstarted，已经start()了啊?
}

Answer 1

Sample as follows:
private void button1_Click(object sender, System.EventArgs e)
{
Form2 f2=new Form2();
f2.MdiParent=this;
System.Threading.Thread x1 = new Thread(new ThreadStart(f2.Show));
x1.Start();
Thread.Sleep(20);
MessageBox.Show(x1.ThreadState.ToString());
}