wp_nav_menu bug: third level and pages/category

Hi!

wp_nav_menu has a big bug and i didn´t find a solution: if you create a custom menu the parent-partent li didn´t get a .current-menu-parent – class. This demo (look at the sidebar) http://test.zeeh.no/demo/ shows the problem. If you show the singel-post (http://test.zeeh.no/demo/?p=82) its not posible to highlight the first parent (page). And if you navigate to page 4, 5 and 6 just the parent get a class, not the parent-parent.

Any solution for this bug? Thanks for help!
Markus