LengthFunction f = app.getRenderer().getLengthFunction() ;
VisualizationViewer vv = null ;
if ( f == null)
vv = new VisualizationViewer(
new TemporalSpringLayout(jungGraph, 50), pr);
else
vv = new VisualizationViewer(
new TemporalSpringLayout(jungGraph,f,50),pr);
return vv;
}