找到最后关注的窗口

Question

有没有办法找到屏幕上最后失去焦点的哪个窗口？我愿意使用以下任何一种方法：

1. pivoke / win apis
2. uiautomaion
3. 任何其他技术

我试过Automation.AddAutomationFocusChangedEventHandler(OnFocusChangedHandler) 但它只提供了有关新窗口的详细信息。我想知道有没有办法让哪个窗口丢失（没有获得）焦点？

有什么建议吗？

由于

Edit1：我想避免民意调查。这将是最后的手段。

Edit2：MSDN说UI自动化提供了这个

Automation.AddAutomationFocusChangedEventHandler(focusHandler);

void OnFocusChange(object src, AutomationFocusChangedEventArgs e)
{
    //MSDN Says that here we get the elements that have lost and received focus. 
    // I am getting the element which received focus by doing

      AutomationElement element = src as AutomationElement;
      //element.Current gives the element that received focus
      //i was not able to get anything which gives the element that lost focus 
}