WPF计时器问题...无法获得正确的毫秒刻度

using System;
using System.Windows;
using System.Windows.Threading;

public partial class MainWindow : Window
{
    private DispatcherTimer timer;

    public MainWindow()
    {
        InitializeComponent();

        timer = new DispatcherTimer();
        timer.Interval = TimeSpan.FromMilliseconds(1);
        timer.Tick += Timer_Tick;
    }

    private void Timer_Tick(object sender, EventArgs e)
    {
        // 在这里执行定时任务
        // 可以获得正确的毫秒刻度
    }

    private void StartButton_Click(object sender, RoutedEventArgs e)
    {
        timer.Start();
    }

    private void StopButton_Click(object sender, RoutedEventArgs e)
    {
        timer.Stop();
    }
}