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How can I use threading to 'tick' a timer to be accessed by other threads?
private DateTime _lastTap;
public void TapHandler()
{
  DateTime now = DateTime.UtcNow;
  TimeSpan span = now - lastTap;
  _lastTap = now;
  if (span < TimeSpan.FromSeconds(1)) {...}
}

private Stopwatch _stopwatch = new Stopwatch();
public void TapHandler()
{
  TimeSpan elapsed = _stopwatch.Elapsed;
  _stopwatch.Restart();
  if (elapsed < TimeSpan.FromSeconds(1)) {...}
}

private static DispatcherTimer clickTimer =
        new DispatcherTimer(
            TimeSpan.FromMilliseconds(SystemInformation.DoubleClickTime),
            DispatcherPriority.Background,
            mouseWaitTimer_Tick,
            Dispatcher.CurrentDispatcher);

    private void Button_MouseDoubleClick(object sender, MouseButtonEventArgs e)
    {
        // Stop the timer from ticking.
        myClickWaitTimer.Stop();

        Trace.WriteLine("Double Click");
        e.Handled = true;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        myClickWaitTimer.Start();
    }

    private static void mouseWaitTimer_Tick(object sender, EventArgs e)
    {
        myClickWaitTimer.Stop();

        // Handle Single Click Actions
        Trace.WriteLine("Single Click");
    }