In the following sample, if the pref size of the pane is 100, Double.MAX_VALUE, I would expect a 100 px wide window that fills the height of the screen. The window is the right width, but the height is zero (or darned close - maybe one or two px). RT-38193 not withstanding, if the pref size is Double.MAX_VALUE, 100 we get a 100px high window that spans the width of the screen (as expected).

    @Override
    public void start(Stage primaryStage) {
        Pane pane = new Pane();
// pane.setPrefSize(Double.MAX_VALUE, 100);
        pane.setPrefSize(100,Double.MAX_VALUE);
        Scene scene = new Scene(pane);
        primaryStage.setScene(scene);
        primaryStage.show();
    }