This is the traffic signal demo, features on my InsideRIA.com blog. The full code for the above is:

import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;

def radius:Number = 50;
def loCols:Color[] = [
    Color.RED , Color.ORANGE , Color.GREEN
];
def hiCols:Color[] = [
    Color.PINK , Color.YELLOW , Color.LIGHTGREEN
];

var n:Group = Group {
    content: for(i in [0..<3]) {
        def cir:Circle = Circle {
            layoutY: i * radius*2
            centerX:radius  centerY:radius
            radius:radius
            fill: bind if(cir.hover) hiCols[i] else loCols[i]
        }
    }
}

Stage {
    scene: Scene {
        content:n
        fill: Color.BLACK
    }
}

Source code is available here.