title: Calling moveTaskToBack twice
body: <p>I'm creating a Home Screen app. I want that this app work as a lockscreen.
  So, when I write down the correct password I use moveTaskToBack to put the task on background what is working perfectly.</p>
  
  <p>Receiving  the Intent.ACTION_SCREEN_ON I start the same instance of activity using</p>
  
  <pre><code>Intent i = new Intent(getApplicationContext(), MainActivity.class);
  i.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
  startActivity(i);
  </code></pre>
  
  <p>What is working too.
  But after that, if I put the correct password again and I call moveTaskToBack, it doesn't work.</p>
  
  <p>Resuming: the first time that I call moveTaskToBack it works well but in the second call, it doesn't.</p>
  
  <p>In my manifesto:</p>
  
  <pre><code>android:launchMode="singleInstance"
  </code></pre>