How to hide a sub level menu from being expanded? When a menu is active, drupal displays the sub-menus of the active menu, but because I use the sub-menus in a separate block via the "menu block" module, I don't want the sub-menu to be shown. How can I do it on server side?

Is there an easy drupal way to do it without touching the theme_menu_link? If not, Is there a way to do it in a module rather in template.php? beside, can some one show me how to write the code?
In the Add/Edit menu_block options, you can specify the Maximum depth of the menu tree to 1.