private Vertex findSingleVertex() {
Vertex vertex = selection.getAnyVertex();
// if there is no selection we select an existing vertex
if (vertex == null) {
vertex = (Vertex) graph.getVertices().next();
}
return vertex;
}
/** Select all graph vertices. */
private void selectAll() {
for (Iterator<? extends Vertex> i = graph.getVertices(); i.hasNext(); ) {
selection.add(i.next());
}
}
