[Lionel]

No big deal. It just adds BOLD to category menu that you are browsing so it makes navigation friendlier
in skin1/customer/category.tpl replace the loop=$categories section with

{section name=cat_num loop=$categories}
{if $smarty.get.cat eq $categories[cat_num].categoryid}
{$categories[cat_num].category}
{else} 
{$categories[cat_num].category}
{/if}
{/section}