Promised an easier, faster, overall better API and text layout engine that replaces the aged TextKit 1 (NSLayoutManager) engine. Text content manager operates on a series of NSTextElement blocks, but again, the only working implementation must inherit from NSTextParagraph, or you're in trouble (runtime assertions). Text scrolls up and down; as you scroll, the visible area displays the layout text. In a scrollview, this results in an update of the scroller to reflect the current document position. I've started to think that TextKit 2 might not be the best tool for text layout, especially when it comes to text editing UI.