private void btPhong_Click(object sender, EventArgs e)
 {
     ThuePhong p = new ThuePhong();
     p.ShowDialog();
     phongCtr.HienThiComboBox(cmbMaPhong);
 }
 //
 // Quan Ly
 //-------------------------------------------------------------------------------------
 private void btNhanPhong_Click(object sender, EventArgs e)
 {
     ThuePhong pnp = new ThuePhong();
     pnp.ShowDialog();
     UpdateListPhong();
 }