There are rendering issues while painting containers (like the accordion) and shapes (like the arc).
They are more visible if the scene and components are rotated and shadows and reflection are used, but the problems are also visible in very basic scenes.
Look at the Screenshot 1 (and the source code for an animated example) for a 'complex' scene with many errors.
If I force the Software-Rendering-Pipeline (with -Dprism.order=j2d) most problems go away, but a new one while animating the yellow arc occurs (see Screenshot 2).

Screenshot 1:
http://imgur.com/dqg9IeD&DjZ7IsD#0

Screenshot 2:
http://imgur.com/dqg9IeD&DjZ7IsD#1


MyHelloToTheWorld.java:
http://pastebin.com/Y8WtYudQ

MyHelloToTheWorldController.java:
http://pastebin.com/nQDeFKt6

FirstGui.fxml:
http://pastebin.com/M3SkLKPz