Surely you can say that -- that constraints are declarative means that resolving them doesn't have to happen in a particular order. The solver could stash away

Surely you can say that -- that constraints are declarative means that resolving them doesn't have to happen in a particular order. The solver could stash away the constraint involving an element that doesn't exist yet, until it does. If this sometimes moves elements that are already displayed, that'd be a problem. Isn't it a problem we're seeing anyway?