Better docs for the class in ctools_ajax_sample_ajax_button_form()

btw, won't it be a better practice to use url():

  $form['url'] = array(
    '#type' => 'hidden',
    '#attributes' => array('class' => array('ctools-ajax-sample-button-url')),
    '#value' => url('ctools_ajax_sample/nojs/animal'),
  );

On a site I develop without the url() the url was not correct.

Rerolled.