I have activated the label proportional to node size setting in SigmaJS because it is how it should display. But it seems that the label size slider is not working anymore because probably it was acting on the absolute unique size of label. I think the best is that this slider multiply all node size by a given factor, thus acting on node size, rather than acting on label size. This allow to improve visualization when node are very densely packed. So we keep label size for the name of this slide but it will act on label size through the node size (since label size is proportional to node size).