private void liênHệToolStripMenuItem_Click(object sender, EventArgs e)
 {
     frm_Lienhe frm = new frm_Lienhe();
     frm.ShowDialog();
 }
        private void liênHệToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frm_Lienhe frm = new frm_Lienhe();

            frm.ShowDialog();
        }