private void btnNewPO_Click(object sender, EventArgs e)
        {
            _frmAddEditPurchaseOrder frmAddEditPurchaseOrder = new _frmAddEditPurchaseOrder()
            {
                MethodType        = MethodType.Add,
                frmPurchaseOrders = this
            };

            frmAddEditPurchaseOrder.ShowDialog();
        }
        private void btnEditPo_Click(object sender, EventArgs e)
        {
            _frmAddEditPurchaseOrder frmAddEditPurchaseOrder = new _frmAddEditPurchaseOrder()
            {
                PurchaseId        = purchaseId,
                MethodType        = MethodType.Edit,
                frmPurchaseOrders = this
            };

            frmAddEditPurchaseOrder.ShowDialog();
        }