wp_nav_menu_post_type_meta_boxes()

function wp_nav_menu_post_type_meta_boxes() {
	$post_types = get_post_types( array( 'show_in_nav_menus' => true ), 'object' );

	if ( ! $post_types )
		return;

	foreach ( $post_types as $post_type ) {
		/**
		 * Filters whether a menu items meta box will be added for the current
		 * object type.
		 *
		 * If a falsey value is returned instead of an object, the menu items
		 * meta box for the current meta box object will not be added.
		 *
		 * @since WP-3.0.0
		 *
		 * @param object $meta_box_object The current object to add a menu items
		 *                                meta box for.
		 */
		$post_type = apply_filters( 'nav_menu_meta_box_object', $post_type );
		if ( $post_type ) {
			$id = $post_type->name;
			// Give pages a higher priority.
			$priority = ( 'page' == $post_type->name ? 'core' : 'default' );
			add_meta_box( "add-post-type-{$id}", $post_type->labels->name, 'wp_nav_menu_item_post_type_meta_box', 'nav-menus', 'side', $priority, $post_type );
		}
	}
}