public void setPositioningElasticity(float elastic) {
        guiPositioningElastic = elastic;
    }
Makes auto GUI positioning happen not immediately, but like an
elastic connected to the headset. Setting to 0 disables (default)
Higher settings make it track the headset quicker.

@param elastic amount of elasticity
jme3-vr/src/main/java/com/jme3/util/VRGuiManager.java