code: public boolean centerWindow () {
  		Group parent = getParent();
  		if (parent == null) {
  			centerOnAdd = true;
  			return false;
  		} else {
  			moveToCenter();
  			return true;
  		}
  	}
docs: Centers this window, if it has parent it will be done instantly, if it does not have parent it will be centered when it will
  be added to stage
  @return true when window was centered, false when window will be centered when added to stage