问运行耗时任务+更新winform

EN

private void button1_Click ( object sender, EventArgs e )
{
   bw.RunWorkerAsync(); // Updates a textbox
   Task<bool> test2 = new Task<bool>( () => _AuthHandler( sender, e, textBox1.Text, textBox2.Text ) );
   try
        {
            test2.Start();
            bool result = test2.Result;
            //bool result = _AuthHandler.Invoke( sender, e, textBox1.Text, textBox2.Text );
            if ( result )
            {

                //Do Somethin..
            }
         }
    catch(Exception e) {
        //Do Something
    }
}
// -------BW TEST CODE --------//
    public void  smthn ()
    {
        textBox3.Text += ".";
    }
    void bw_DoWork ( object sender, DoWorkEventArgs e )
      {
          for(int i = 0;; i++) 
          {
              bw.ReportProgress( i );
              Thread.Sleep( 250 );
          }
       }

    bool result = false;
    void bw_RunWorkerCompleted ( object sender, RunWorkerCompletedEventArgs e )
    {
        MessageBox.Show( "Result Set" );
        result = (bool)e.Result;
    }
    void bw_ProgressChanged ( object sender, ProgressChangedEventArgs e )
    {
        if ( textBox3.InvokeRequired )
        {
            this.Invoke( new Action( smthn ) );
        }
        else
        {
            smthn();
        }
    }