title: the hidden Navigationbar is appeared when toolbar menu button is clicked
body: <p>I have used the method presented <a href="https://stackoverflow.com/q/21724420/3990512">here</a> to hide Navigationbar. It works properly but when I tap the context menu button (three vertical points in the right side of the toolbar), the navigationbar is appeared again. </p>
  
  <p>I have used the code: </p>
  
  <pre><code>    View decorView = getWindow().getDecorView();
      decorView.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);
  </code></pre>
  
  <p>in <code>onResume()</code>, <code>onCreate()</code>, <code>onOptionsItemSelected()</code>, <code>onWindowFocusChanged()</code>. </p>
  
  <p>If all of menu items are set to <code>app:showAsAction="always"</code> the Navigationbar is never appeared but when some are shown in the list, it appeard.</p>