XAMLDebuggingTool.cs

using System.Collections.Generic;
using System.Windows;

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            List<int> numbers = new List<int>();
            for (int i = 0; i < 5; i++)
            {
                numbers.Add(i);
            }
            TestListBox.ItemsSource = numbers;
        }
    }
}