private void btnRemove_Click(object sender, RoutedEventArgs e)
        {
            AirlinerOrder order = (AirlinerOrder)((Button)sender).Tag;

            this.orders.Remove(order);

            showOrders();
        }
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            AirlinerOrder order = (AirlinerOrder)value;

            return(new ValueCurrencyConverter().Convert(order.Type.Price * order.Amount));
        }