private void pbPOrder_Click(object sender, EventArgs e)
        {
            pnlMain.Controls.Clear();
            DetailsProductOrder dp = new DetailsProductOrder();

            dp.TopLevel        = false;
            dp.Dock            = DockStyle.Fill;
            dp.FormBorderStyle = FormBorderStyle.None;
            pnlMain.Controls.Add(dp);
            dp.Show();
        }
 private void btnClose_Click(object sender, EventArgs e)
 {
     DetailsProductOrder d = new DetailsProductOrder();
     d.Visible = true;
     this.Visible = false;
 }