private void ordersGrid_MouseDoubleClick(object sender, MouseButtonEventArgs e)
        {
            var order = this.ordersGrid.SelectedItem as Order;

            if (order == null)
            {
                return;
            }

            if (productsWindow == null)
            {
                productsWindow       = new ProductsWindow();
                productsWindow.Owner = this;
            }

            productsWindow.ViewModel = new ProductsWindowViewModel(order.OrderID);
            productsWindow.Show();
        }