Hi, I am building my first zen cart and am learning loads. Yellow1912, I have been playing around with your contrib. and it's great, thanks!.
I have been trying to display ONLY the first sub-cat level all the time in the header using :

$_SESSION['category_tree']->build_category_string('ul', 'li', '', $_GET['cPath']{0}, 0)

But get the next level with it expanded also. Any way of just giving the first sub-cats only after selection of top cat elsewhere on the page?
I have also tried:
$_SESSION['category_tree']->build_category_string('ul', 'li', '', $_GET['cPath']{0}, 1)

Thanks, DanP

p.s. I am also looking forward to script for 'list all products under category selected'