title: How to hide the soft-key bar on Android phone?
body: <p>　<img src="https://i.stack.imgur.com/sCJl8.png" alt="enter image description here"></p>
  
  <p>When my app starts, I'd like to hide the soft keys bar (in red rectangle) to have a larger screen.</p>
  
  <ol>
  <li><p>How can I hide it?</p></li>
  <li><p>Do I need to show the bar purposely when the app quits? Or it will restore itself automatically after the app quits?</p></li>
  </ol>
  
  <p>Android 4.1, with no hardware keys on phone front.</p>