@Override
    public void loseFocus(){
        if (lostFocusBehavior != LostFocusBehavior.Disabled){
            if (lostFocusBehavior == LostFocusBehavior.PauseOnLostFocus) {
                paused = true;
            }
            context.setAutoFlushFrames(false);
        }
    }
Force the focus lost for the application. Internal use only.
jme3-vr/src/main/java/com/jme3/app/VRApplication.java