This comes in handy if you are using a list_page menu and need to change the style of menu elements that have children, liks add an arrow. This needs to be in the functions file.
add_filter('page_css_class', 'nice_navigation_page_css_class', 10, 2); /** * adds class "page-has-children" to all pages that have children * @param array $class. The page css class being modified, passed as an array from Walker_Page * @param object $page. The page object passed from Walker_Page * @return array Returns the new page css class. */ function nice_navigation_page_css_class($class, $page) { // check if current page has children $children = get_pages('child_of='.$page->ID); if (sizeof($children) > 0) { $class[] = "page-has-children"; } return $class; }