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

            frm.ShowDialog();
        }