title: Detecting when system buttons are visible while using 'immersive mode'
body: <p>I'm currently using immersive mode (API 19) for one of my Activities as follows:</p>
  
  <pre><code>getWindow().getDecorView()
              .setSystemUiVisibility(
                      View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                              | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                              | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                              | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                              | View.SYSTEM_UI_FLAG_FULLSCREEN
                              | View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
                              | View.INVISIBLE);
  </code></pre>
  
  <p>This hides the system buttons and notification bar until the user swipes for them back. This works fine, however I wish to detect when the user makes the buttons visible again. I've tried a <code>OnSystemUiVisibilityChangeListener</code> but it does not trigger for this particular event.</p>
  
  <p>Any ideas?</p>