Small NetBeans Visual Library Resize Sample

When the mouse is moved over this widget, resize borders appear, and the widget can be resized:

When the mouse moves away from the widget, the resize borders disappear:

setLayout(new BorderLayout());

Scene scene = new Scene();

LayerWidget baseLayer = new LayerWidget(scene);

Widget widget = new Widget(scene);
widget.setBorder(BorderFactory.createLineBorder(1));
widget.setPreferredLocation(new Point(10, 20));
widget.setPreferredBounds(new Rectangle(30, 30));
widget.getActions().addAction(ActionFactory.createResizeAction());
widget.getActions().addAction(ActionFactory.createMoveAction());
WidgetAction hoverAction = ActionFactory.createHoverAction(new TwoStateHoverProvider() {
    @Override
    public void unsetHovering(Widget w) {
        w.setBorder(BorderFactory.createLineBorder(1));
    }
    @Override
    public void setHovering(Widget w) {
        w.setBorder(BorderFactory.createResizeBorder(8, Color.BLACK, false));
    }
});
widget.getActions().addAction(hoverAction);
scene.getActions().addAction(hoverAction);
baseLayer.addChild(widget);

scene.addChild(baseLayer);

add(scene.createView(), BorderLayout.CENTER);