> Is this similar to the "dirty rectangles" technique? Yes. > It seems difficult to implement some sort of scene system (for either an app, game or general GU

> Is this similar to the "dirty rectangles" technique? Yes. > It seems difficult to implement some sort of scene system (for either an app, game or general GUI) that given a single key press can determine a minimum bounding box of changes on the screen no matter what the scene is, and is able to render just that bounding box. I don't think it's that bad. In the days before hardware graphics, basically every 2D sprite engine used in every computer game you liked had to do this logic. Text editors are a harder case in some ways because of line wrapping, but the editor does need to figure out where everything goes spatially in order to render, so extending that to tell which things have not moved is, I think, not that difficult.