function add_backend_header_parts()
 {
     $cssfilename = TwitterPluginFileAccess::get_file_from_template('tweeter/serendipity_event_twitter_tweeter.css', $this->get_config('plugin_rel_url'));
     echo '<link rel="stylesheet" type="text/css" href="' . $cssfilename . '" />' . "\n";
     $jsfilename = $this->get_config('plugin_rel_url') . '/tweeter/serendipity_event_twitter_tweeter.js';
     echo '<script type="text/javascript" src="' . $jsfilename . '"></script>' . "\n";
 }