///--------------------------------------------------------------------
/// <summary>
/// Register for events of interest.
/// </summary>
/// <param name="targetControl">
/// The automation element of interest.
/// </param>
///--------------------------------------------------------------------
private void RegisterForAutomationEvents(
    AutomationElement targetControl)
{
    AutomationEventHandler eventHandler = 
        new AutomationEventHandler(OnWindowOpenOrClose);
    Automation.AddAutomationEventHandler(
        WindowPattern.WindowClosedEvent, 
        targetControl, TreeScope.Element, eventHandler);
    Automation.AddAutomationEventHandler(
        WindowPattern.WindowOpenedEvent, 
        targetControl, TreeScope.Element, eventHandler);
}

///--------------------------------------------------------------------
/// <summary>
/// AutomationEventHandler delegate.
/// </summary>
/// <param name="src">Object that raised the event.</param>
/// <param name="e">Event arguments.</param>
///--------------------------------------------------------------------
private void OnWindowOpenOrClose(object src, AutomationEventArgs e)
{
    // Make sure the element still exists. Elements such as tooltips
    // can disappear before the event is processed.
    AutomationElement sourceElement;
    try
    {
        sourceElement = src as AutomationElement;
    }
    catch (ElementNotAvailableException)
    {
        return;
    }
    
    if (e.EventId == WindowPattern.WindowOpenedEvent)
    {
        // TODO: event handling
        return;
    }
    if (e.EventId == WindowPattern.WindowClosedEvent)
    {
        // TODO: event handling
        return;
    }
}