private void tìmKiếmToolStripMenuItem_Click(object sender, EventArgs e)
 {
     frm_Timkiem tk = new frm_Timkiem();
     tk.ShowDialog();
 }
        private void tìmKiếmToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frm_Timkiem tk = new frm_Timkiem();

            tk.ShowDialog();
        }