----- HelloProgressBar -----

To reproduce, move mouse over progress bars :

    java -ea -cp ../../../artifacts/sdk/rt/lib/ext/jfxrt.jar:dist/HelloWorld.jar helloworld.HelloProgressBar
    Exception in runnable
    java.lang.NullPointerException
        at javafx.scene.Node.impl_intersects(Node.java:4369)
        at javafx.scene.Node.impl_intersectsBounds(Node.java:4549)
        at javafx.scene.layout.Region.impl_pickNodeLocal(Region.java:2156)
        at javafx.scene.Node.impl_pickNode(Node.java:4339)
        at javafx.scene.layout.Region.impl_pickNodeLocal(Region.java:2161)
        at javafx.scene.Node.impl_pickNode(Node.java:4339)
        at javafx.scene.Parent.impl_pickNodeLocal(Parent.java:676)
        at javafx.scene.Node.impl_pickNode(Node.java:4339)
        at javafx.scene.Scene$MouseHandler.pickNode(Scene.java:3629)
        at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3276)