如何从子窗体关闭程序主窗体窗口

private void button1_Click(object sender, EventArgs e)
        {//显示子窗体
            Form2 MyForm = new Form2();
            //主窗体作为模式对话框的拥有者
            MyForm.ShowDialog(this);
        }

 

        private void button1_Click(object sender, EventArgs e)
        {//关闭当前(子)窗体
            this.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        {//关闭主(父)窗体
            Form1 MyForm = (Form1)this.Owner;
            MyForm.Close();
        }