title: show navigation drawer on physical menu button
body: <p>I want to show the navigation drawer when the user clicks on the physical menu button, I override the menu button like the following :</p>
  
  <pre><code> @Override
      public boolean onKeyDown(int keyCode, KeyEvent event) {
          if ( keyCode == KeyEvent.KEYCODE_MENU ) {
  
                  // some code here to show navigation drawer
  
              return true;
          }
          return super.onKeyDown(keyCode, event);
      }
  </code></pre>
  
  <p>But I don't know what should I do to show the navigation drawer inside this method.</p>