18. The method of claim 13 , wherein the layout component hierarchy comprises a parent node and child nodes, the aggregating comprising propagating at least one of the complexity values of the child nodes in the layout component hierarchy to the parent node.
18. The method of claim 13 , wherein the layout component hierarchy comprises a parent node and child nodes, the aggregating comprising propagating at least one of the complexity values of the child nodes in the layout component hierarchy to the parent node. 21. The method of claim 18 , wherein the propagating at least one of the complexity values comprises propagating a maximum complexity value of the child nodes to the parent node.