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