Comment 1 for bug 530930

It is not trivial to introduce edge weights in the KK layout because the energy function being optimized includes a single term for both edges and non-edges (i.e. there is no distinction between them), so we have to specify weights for non-edges as well as edges. Of course we can say that non-edges always have a weight of 1 and we allow the user to tweak the weights of the terms corresponding to edges only.