// Clone the entity to avoid messing with it.
    $entity_type = $element['#entity_type'];
    if (!isset($form_state[$entity_type])) {
      return;
    }
    $cloned_entity = clone $form_state[$entity_type];

    $element['fixed_field'] = field_view_field($entity_type, $cloned_entity, $field['field_name'], $display, $langcode);
    $element['fixed_field']['#ajax'] = array(
      'callback' => 'fixed_field_ajax_get_value',
      'event' => 'click',
      'method' => 'replace',
      'wrapper' => 'fixed_field-div',
    );
    $element['fixed_field']['#prefix'] = '<div id="fixed_field-div">';
    $element['fixed_field']['#suffix'] = '</div>';
    $output = $element;

    if (($settings['user_edit_perm']==TRUE) && user_access('edit_fixed_content')) {
      $output['edit'] = array(
        '#markup' => '<input type="button" onclick="alert()" value="'.t('Edit').'" />',
      );
    }
  }

  return $output;
}

function fixed_field_ajax_get_value($form, $form_state) {
  return array('#markup'=>'qwertyuiop');
}