title: Detect a right-click on Ace editor
body: <p>Is there a way to detect a right-click event on Ace editor?</p>
  <p>I've being trying to add a listener like this:</p>
  <pre class="lang-js prettyprint-override"><code>  editor.session.addEventListener('contextmenu', function(e) {
        e.preventDefault();
        alert('success!');
        return false;
    }, false);
  </code></pre>
  <p>and this</p>
  <pre class="lang-js prettyprint-override"><code>  editor.addEventListener('contextmenu', function(e) {
        e.preventDefault();
        alert('success!');
        return false;
    }, false);
  </code></pre>
  <p>but without success.</p>