private void checkOutButton_Click(object sender, EventArgs e)
        {
            CustomerCheckOut form = new CustomerCheckOut(Model);

            form.Dock = DockStyle.Fill;
            form.MdiParent = this.MdiParent;
            form.Show();
            form.WindowState = FormWindowState.Maximized;
        }
 private void button7_Click(object sender, EventArgs e)
 {
     CustomerCheckOut customerCheckOut = new CustomerCheckOut(Model);
     customerCheckOut.Dock = DockStyle.Fill;
     customerCheckOut.MdiParent = this.MdiParent;
     customerCheckOut.Show();
     customerCheckOut.WindowState = FormWindowState.Maximized;
 }