}
@Override
public void execute() {
Map<SNode,Point2D.Double> diffs = new HashMap<SNode,Point2D.Double>();
SNode first = context.getSelection().firstItem();
double center = first.getTransformedBounds().getCenterY();
for(SNode node: context.getSelection().items()) {
double c2 = node.getTransformedBounds().getCenterY();
double cdiff = c2-center;
node.setTranslateY(node.getTranslateY()-cdiff);
diffs.put(node,new Point2D.Double(0,-cdiff));