FlowPane doesn't layout scaled children properly

I have a issue with the flowpane layout in JavaFX(2.2). I'd like to scale the children nodes within it(e.g with a slider). The scaling part works fine but when they are scaled the children starts to clip each other. Which is really not what I want. What I want is to be able to scale them without letting them overlap each other. How do I solve this ?

Here is an example app that shows this behaviour:

public class App extends Application
{
    public static void main( String[] args )
    {
        launch();
        System.out.println( "Hello World!" );
    }

    @Override
    public void start(Stage stage) throws Exception {


        FlowPane flowPane = new FlowPane();

        Slider slider = new Slider(0.1, 2.0, 1.0);
        slider.setMajorTickUnit(0.1);


        flowPane.getChildren().add(slider);



        final Circle circleA = new Circle(20, Color.RED);

        circleA.scaleXProperty().bind(slider.valueProperty());
        circleA.scaleYProperty().bind(slider.valueProperty());

        Circle circleB = new Circle(20, Color.BLACK);
        circleB.scaleXProperty().bind(slider.valueProperty());
        circleB.scaleYProperty().bind(slider.valueProperty());


        flowPane.getChildren().add(circleA);
        flowPane.getChildren().add(circleB);

        Scene scene = SceneBuilder.create().root(flowPane).build();

        stage.setScene(scene);
        stage.setMinHeight(300);
        stage.setMinWidth(300);
        stage.show();
    }
}