1) run EnsembleApp
2) run 3D 'Xylophone' example
3) don't wait until Xylophone is done spinning (not sure this in necessary)
4) close EnsembleApp using close button
5) BUG: NPE

java.lang.NullPointerException
at com.sun.javafx.tk.quantum.PaintCollector.done(PaintCollector.java:300)
at com.sun.javafx.tk.RenderJob.run(RenderJob.java:77)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at com.sun.javafx.tk.quantum.QuantumRenderer$PipelineRunnable.run(QuantumRenderer.java:125)
at java.lang.Thread.run(Thread.java:744)

This bug doesn't happen all the time. I tried to get it on Mac a few times and could not.