WordPress: wp_list_pages | Custom Post Type | Class Names

custom_list_pages.php

function kct_page_css_class( $css_class, $page, $depth, $args, $current_page ) {
  if ( !isset($args['post_type']) || !is_singular($args['post_type']) )
    return $css_class;

  global $post;
  $current_page  = $post->ID;
  $_current_page = $post;
  _get_post_ancestors($_current_page);

  if ( isset($_current_page->ancestors) && in_array($page->ID, (array) $_current_page->ancestors) )
    $css_class[] = 'current_page_ancestor';
  if ( $page->ID == $current_page )
    $css_class[] = 'current_page_item';
  elseif ( $_current_page && $page->ID == $_current_page->post_parent )
    $css_class[] = 'current_page_parent';

  return $css_class;
}
add_filter( 'page_css_class', 'kct_page_css_class', 10, 5 );