title: why "onPause" is not called in following situation?
body: <p>By the document, "onPause" is called, when:</p>
  
  <blockquote>
    <p>when the system is about to start resuming a previous activity.</p>
  </blockquote>
  
  <p>Compared to "onStop", the difference is:</p>
  
  <blockquote>
    <p>Called when the activity is no longer visible to the user, because another activity has been resumed and is covering this one.</p>
  </blockquote>
  
  <p>But when I long-press HW-Home key and the "recent apps" shows up, 
  the "onPause" is not called.</p>
  
  <p>At this moment, I can no long able to interact with the original activity,
  but it is still visible.</p>
  
  <p>I am confused by this situation.
  Please help to explain.</p>
  
  <p>Thank you very much.
  BR,
  Henry</p>