Trees of "dumb" rectangles don't seem very suitable for responsive or adaptive layouts in which the hierarchical structure is built before deciding rectangle si

Trees of "dumb" rectangles don't seem very suitable for responsive or adaptive layouts in which the hierarchical structure is built before deciding rectangle sizes. For a retained mode GUI traditional container widgets and layout managers negotiating sizes with child widgets seem a more general technique; for an immediate mode GUI there is no obvious advantage over explicit and more general size computations at the same abstraction level.