That link is for create theme sidebar widgets, not a nav menu meta box which is what I have found out I need to do by digging into the core code.
Thanks anyway
Could you please share what you have found as I believe I’ve ran into the same issue? Thanks!
I’ve been able to create a meta box using the code on http://codex.wordpress.org/Function_Reference/add_meta_box as an example, and adding it to the ‘nav-menu’ post type.
It shows up fine, but unable to add it to a menu. Missing a hook somewhere but I cannot see where.
Standard meta boxes are defined in /wp-admin/includes/nav-menu.php I even tried copying the custom link box, but it did nothing.
Maybe someone else can see something I missed.
Cool, but not free. At least it shows it can be done.