If two traces are not grouped, you can move them arbitrarily close together (without overlap) and you can also have them have a partial or full overlap, both of which can be very useful at times. However when multiple traces are in a trace group that is no longer possible (you'd have to ungroup them). It would be nice if there were a way to have both, grouping *and* arbitrary spacing between the traces in the group, as well as arbitrary overlap between the traces in the group.