active parent page when clicked on childpage

Question

Hi there Wordpress guru's,

i running up against a problem. I've my parent pages in the header.php and childpages in page.php. when i clicked on one of the subpages in a parent page i want that my parent page stay active. How can i get that done?

in my header.php i've the following code:

<ul id="mainNav">
 <?php wp_list_pages('sort_column=menu_order&exclude=2&depth=1&title_li='); ?>
</ul>

page.php

<?php if($post->post_parent)
            $children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0"); else
            $children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
            if ($children) { ?>
            <div id="subPages">
            <ul>
            <li class="root"><?php echo '<a href="'.get_permalink($post->post_parent).'">'.get_the_title($post->post_parent).'</a>';?></li>
            <?php echo $children; ?>
            </ul>
            </div>
            <?php } else { ?>
        <?php } ?>

U can see the example : here when you click on one of the subpages i want that the parent page (the tab above) stays active.

tnx for advance.

Answer 1

http://codex.wordpress.org/Function_Reference/wp_list_pages#Markup_and_styling_of_page_items

style .current_page_parent and/or .current_page_ancestor the same as .current_page_item