@Override
                  public Object call() throws Exception {
                    guiViewPort.clearScenes();
                    guiViewPort.attachScene(node);
                    guiNode = node;
                    return null;
                  }
Set the GUI node that is displayed within the GUI viewport.
Calling this method involve clearing all the scenes previously attached to the gui viewport.
@param node the GUI node to attach.
@see #getGuiNode()
jme3-vr/src/main/java/com/jme3/app/VRApplication.java