QVariant Node::itemChange(GraphicsItemChange change,
const QVariant &value)
{
if (change == ItemPositionHasChanged) {
foreach (Link *link, myLinks)
link->trackNodes();
}
return QGraphicsItem::itemChange(change, value);
}
Whenever the user drags a node, the itemChange() handler is called with ItemPositionHasChanged as the first argument.