JavaFX 2.0 :: Continuous Drawing In Custom NGRegion

I am subclassing a Pane to be able to use my custom NGRegion:
 
public class MyPane extends Pane {
@Override
public NGNode impl_createPeer() {       
return new MyNGRegion();
}
}
 
in MyNGRegion i override renderContent(Graphics g) for custom drawing
 
@Override
protected void renderContent(Graphics g) {
/* custom drawing */
}
 
The custom NGRegion gets drawn one time, but i want to continuously draw on every pulse.
 
i already tried a lot of things, but don't see how to do it properly:
 
using -Dprism.forcerepaint=true did not work.

overriding clearDirty() and set it