function _phptemplate_variables($hook, $vars) {
  switch($hook) {
    case 'node':
      if (module_exists('service_links')) {
        $vars['service_links'] = theme('links', service_links_render($vars['node'], TRUE));
      }
      break;
  }

  return $vars;
}

function zen_variables($hook, $vars) {
  $vars['subtheme_directory'] = path_to_subtheme();

  switch ($hook) {
    case 'page':
      // Add main Zen styles.
      drupal_add_css($vars['directory'] .'/tabs.css', 'theme', 'all');
      // Then add styles for this sub-theme.
      drupal_add_css($vars['subtheme_directory'] .'/layout.css', 'theme', 'all');
      drupal_add_css($vars['subtheme_directory'] .'/icons.css', 'theme', 'all');
      drupal_add_css($vars['subtheme_directory'] .'/zen-classic.css', 'theme', 'all');
      // Optionally add the fixed width CSS file.
      if (theme_get_setting('zen_classic_fixed')) {
        drupal_add_css($vars['subtheme_directory'] .'/zen-fixed.css', 'theme', 'all');
      }
      $vars['css'] = drupal_add_css();
      $vars['styles'] = drupal_get_css();
      // Avoid IE5 bug that always loads import print stylesheets
      $vars['head'] = zen_add_print_css($vars['subtheme_directory'] .'/print.css');

      if (module_exists('advanced_forum')) {
      $vars = advanced_forum_addvars($hook, $vars);
      }

  }
  return $vars;