The following source code came in handy for me, when I decided I wanted to show only the top level category in the top navigation menu of a magento store, and only show the child categories in a page whenever the top level category is clicked. This is very useful if one of your top categories contains a lot of subcategories, that will create a giant list in the drop-down menu when the visitor hovers over it. First you have to set the sub categories as active in the magento administrator panel, but the option “Include in navigation menu” should...