private void btnDelete_Click(object sender, EventArgs e)
        {
            FChangeNhomHang fadd = new FChangeNhomHang();

            fadd.AddThongTin(new string[] { btnDelete.Text, txtMaNhom.Text, txtTenNhom.Text });
            fadd.MdiParent = main;
            fadd.main      = main;
            this.Close();
            fadd.Show();
        }
        private void btnAdd_Click(object sender, EventArgs e)
        {
            //this.Hide();
            FChangeNhomHang fadd = new FChangeNhomHang();

            fadd.AddThongTin(new string[] { btnAdd.Text, "", "" });
            fadd.MdiParent = main;
            fadd.main      = main;
            //fadd.fnhomhang.MdiParent = main;
            this.Close();
            fadd.Show();
        }