If you’re getting a NullPointerException stacktrace like the one below while using the Netbeans Visual Library to create your own GraphScene, check that your adding your widgets propertly to scene. A good idea is to use LayerWidgets, declaring them in the constructor of your GraphScene:
mainLayer = new LayerWidget(this);
addChild(mainLayer);
connectionLayer = new LayerWidget(this);
addChild(connectionLayer);
and then add the widgets [...]
