action.php

<?php
require_once(DOKU_PLUGIN.'action.php');

class action_plugin_nspages extends DokuWiki_Action_Plugin {

    /**
     * Register its handlers with the dokuwiki's event controller
     */
    function register(Doku_Event_Handler $controller) {
        $controller->register_hook('TOOLBAR_DEFINE', 'AFTER',  $this, 'insert_button', array());
        $controller->register_hook('PLUGIN_POPULARITY_DATA_SETUP', 'AFTER', $this, 'usage_data');
    }

    function insert_button(& $event, $param) {
      $event->data[] = array (
          'type' => 'insert',
          'title' => 'nspages',
          'icon' => '../../plugins/nspages/images/tb_nspages.png',
          'insert' => $this->getConf('toolbar_inserted_markup')
          );
    }

    function usage_data(&$event){
      $plugin_info = $this->getInfo();
      $event->data['nspages']['version'] = $plugin_info['date'];
    }
}