@nriley I think it’s required unless you implement the “group”/header styling yourself. Maybe iTunes still uses its own framework.
@stormchild Alas, hover-to-discover used to be restricted to Web and Windows apps.
Lion's rollover source list header “Show” buttons seem to be a failure. Lots of customers think their collapsed mailboxes have been deleted.
@reitshamer And yet they rejected a third-party calendar app for having too much latency.