private void btMaLoaiDatTiec_Click(object sender, EventArgs e)
 {
     LoaiDatTiec ldt = new LoaiDatTiec();
     ldt.ShowDialog();
     ldtCtrl.HienThiComboBox(cmbMaLoaiDatTiec);
 }
 private void buttonX1_Click(object sender, EventArgs e)
 {
     LoaiDatTiec ldt = new LoaiDatTiec();
     ldt.ShowDialog();
 }