GDN version 1.4+
This filter is used in Meta Category. You can change category items in meta.
function my_meta_categories($categories){
foreach($categories as $key => $category){
if($category->parent > 0){
unset($categories[$key]);
}
}
return $categories;
}
add_filter( 'jaw_meta_categories', 'my_meta_categories',10 );
In meta will be shown only main categories (not childs)
List of all hooks you can find HERE