public class FU : System.Windows.Forms.Form {
  Thread th;
  public FU()
  {
	this.th = new Thread(new ThreadStart(this.mega));
	this.th.Start();
  }

   /* ..... */
 
   private mega()
   {
      	try
	{
		Form cf = new Form("asdf");
		cf.MdiParent = this;
		cf.Show();
	} 
	catch (Exception e)
	{
		MessageBox.Show("Cannot create MDI" + e);
	}
   }
}