List with categories and limited number of items

Question

I'd like to have a list in WPF (listbox, listview, anything) that can display items grouped on categories, but also having a limited number of items per category (let's say 5). If there are more items in a category then only display the first (5) and have a button or link to expand to more (or display them in a new container or window). Is that possible in a fairly simple way, or does it require a custom control?