private void finishOrderButton_Click(object sender, EventArgs e)
        {
            // Finish or unfinish order based on what it currently is.
            if (isDone)
            {
                order_Service.FinishOrder(this.orderItem.OrderID);
            }
            else
            {
                order_Service.UnFinishOrder(this.orderItem.OrderID);
            }

            // Update our data on our main window so the user sees the changes.
            mainWindow.UpdateData();

            // Close this form.
            this.Close();
        }