private void Order_Price_Group(object sender, RoutedEventArgs e)
        {
            OrderView.Filter = null;
            OrderView.GroupDescriptions.Clear();
            OrderView.SortDescriptions.Add(new SortDescription("Amount", ListSortDirection.Descending));

            ProductPriceGrouper grouper = new ProductPriceGrouper {
                Interval = 2000
            };

            OrderView.GroupDescriptions.Add(new PropertyGroupDescription("Amount", grouper));
        }
        private void Group_Product(object sender, RoutedEventArgs e)
        {
            RadioButton radio = sender as RadioButton;

            if (radio.Name == "Group_Category")
            {
                ProductView.GroupDescriptions.Clear();
                ProductView.GroupDescriptions.Add(new PropertyGroupDescription("Category"));
            }
            else if (radio.Name == "Group_Price")
            {
                ProductView.Filter = null;
                ProductView.GroupDescriptions.Clear();
                ProductView.SortDescriptions.Add(new SortDescription("Price", ListSortDirection.Descending));

                ProductPriceGrouper grouper = new ProductPriceGrouper {
                    Interval = 200
                };
                ProductView.GroupDescriptions.Add(new PropertyGroupDescription("Price", grouper));
            }
        }