private void btnThongTinHoaDon_Click(object sender, EventArgs e)
        {
            FormHDX FHDX = new FormHDX();

            FHDX.Show();
            this.Hide();
        }
        private void btnBack_Click(object sender, EventArgs e)
        {
            if (timer1.Enabled == true)
            {
                timer1.Enabled = false;
                timer1.Stop();
                Stream.Stop();
            }
            FormHDX FHDX = new FormHDX();

            FHDX.Show();
            TTTK.MaHDX    = 0;
            TTTK.MoFormRP = 0;
            this.Close();
        }