private void button8_Click(object sender, EventArgs e)
 {
     QuanLyTacGia fm = new QuanLyTacGia();
     fm.ShowDialog();
 }
        private void button8_Click(object sender, EventArgs e)
        {
            QuanLyTacGia fm = new QuanLyTacGia();

            fm.ShowDialog();
        }