Parent navigation doesn’t open when visiting navigation sub items

When using multilevel (2 or 3 levels) navigation, when user clicks sub menu link, current navigation item isn’t show because parent navigation is closed, so user have to press again widget toggler link.

Dirty way to fix this:

(function($) {

        $( document ).ready(function() {
               $( "li.current_page_item" ).each(function( index ) {
                  $(this).parent('.sub-menu').slideToggle('fast');
                  $(this).parent().parent('.sub-menu').slideToggle('fast');
                });

                $( "li.current-menu-parent" ).each(function( index ) {
                  $(this).parent('.sub-menu').slideToggle('fast');
                });

        });
})(jQuery);