title: Xamarin close Android application on back button
body: <p>I tried 3 different ways             </p>
  
  <pre><code>if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
      System.Environment.Exit(0);
  
  public override void OnBackPressed()
  {
      Finish();
  }
  
  public override bool OnKeyDown(Keycode keyCode, KeyEvent e)
  {
      if (keyCode == Keycode.Back)
      {
              System.Environment.Exit(0);
              return true;
      }
      return base.OnKeyDown(keyCode, e);
  }
  </code></pre>
  
  <p>None of the above seems to be working</p>