In the layout section, you say that the various steps should iterate through the widget tree in a preorder fashion (top-down). But downward-dependent sizes like `UI_SizeKind_ChildrenSum` seem like they should be computed in a postorder fashion (bottom-up). After all, if any children use downward-dependent sizes as well, I'd want to resolve those first before computing sizes on the parent. Is that an exception to the preorder rule, or am I misunderstanding something?
In the layout section, you say that the various steps should iterate through the widget tree in a preorder fashion (top-down). But downward-dependent sizes like `UI_SizeKind_ChildrenSum` seem like they should be computed in a postorder fashion (bottom-up). After all, if any children use downward-dependent sizes as well, I'd want to resolve those first before computing sizes on the parent. Is that an exception to the preorder rule, or am I misunderstanding something?