form1:
private void button1_Click(object sender, System.EventArgs e)
        {
            Form2 frm = new Form2();
            frm.OnSendString += (text) => { textBox1.Text = text; };
            frm.Show();
        }

form2:
        public delegate void SendStringHandler(String text);
        public event SendStringHandler OnSendString;

        private void button1_Click(object sender, EventArgs e)
        {
            if (OnSendString != null)
            {
                OnSendString("在WinForms程序里实现窗体传值的最佳实践");
            }
        }

m_dlg.TextBoxChanged += new EventHandler(
  (sender1, e1) =>
  { richTextBox1.Text = m_dlg.TextBoxValue; }
  );

=>相当于


m_dlg.TextBoxChanged += new EventHandler(m_dlg_textboxchanged);

...

private void m_dlg_textboxchanged(object sender1, EventArgs e1)
{
    richTextBox1.Text = m_dlg.TextBoxValue;
}