Code to generate current-cat-parent?

Hi,

I’ve searched and can’t find the answer for my situation.

I have a category dropdown menu item, but cannot seem to get the code to generate “current-cat-parent” for the parent menu item when a submenu item is clicked.

I want to do this so I can highlight the parent menu item when a submenu child is clicked.

Here’s my code:

<li class="cat-item">
<a href="#">Work</a>
<ul class="children">
<?php wp_list_categories("exclude=$blog_ID&title_li=");('orderby=name&title_li=');
$this_category = get_category($cat);
if (get_category_children($this_category->cat_ID) != "") {
echo "<ul>";
wp_list_categories('orderby=id&show_count=0&title_li=
&use_desc_for_title=1&child_of='.$this_category->cat_ID);
echo "</ul>";
}
?>
</ul>
</li>

I think I have the right css, but because the “current-cat-parent” code isn’t being generated when I click on a subcategory, the css can’t style the parent menu item.

Any help would be greatly appreciated!