private void copyItemsButton_ItemClick(object sender, DevExpress.XtraBars.ItemClickEventArgs e) { SalesOrder salesOrder = (SalesOrder)m_order.GetContract <SalesOrder>(); PurchaseOrder purchaseOrder = (PurchaseOrder)m_order.GetContract <PurchaseOrder>(); if (salesOrder == null | purchaseOrder == null) { MessageBox.Show("This order does not contain a sales order and a purchase order", Application.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Exclamation); return; } if (salesOrder.CartItems.Count > 0) { purchaseOrder.CopyItemsFromSalesOrder(salesOrder); } else { salesOrder.CopyItemsFromPurchaseOrder(purchaseOrder); } }