private void btnXoa_Click(object sender, EventArgs e)
 {
     try
     {
         DeTai detai = DeTaiController.getExistDT(listDeTai.SelectedItems[0].SubItems[0].Text.Trim());
         this.listDeTai.SelectedItems[0].Remove();
         DeTaiController.DeleteDeTai(detai);
     }
     catch { }
 }