Plugin: Category Parent Style
Plugins
This plugin applies a custom CSS-class to categories that have subcategories using {exp:weblog:categories}.
3-level expanding category based menu
Plugins
In a project I have some “static pages” organized using categories and subcategories. There is a weblog for the content of the pages and every entry has an accompanying category. The menu was generated with the nested {exp:weblog:categories}-tag. The currently active menu-item had to have a different style associated. You’d normally do this by comparing the category name with an URL-segment.
However a further requirement was that the menu was supposed to expand. At first only the parent categories are to be shown. When a category is selected, its subcategories should show up. Only the subcategories of the selected category and only the 1st-level subcategories. When a 1st-level subcategory is selected, the corresponding 2nd-level subcategories are supposed to show up - if there are any.
I found no way to implement this behaviour using built-in functionality and hard-coding the menu was not an option since the process of adding a new page into the hierachy should be limited to adding a new category and writing an entry assigned to this category.
I ended up with writing a little plugin.