private void preOrder() {
            if (popups.isEmpty()) return;
            for (int i = 0 ; i < popups.size() ; i++) {
                switch (popupLocation) {
                    case TOP_LEFT: case TOP_CENTER: case TOP_RIGHT: popups.get(i).setY(popups.get(i).getY() + height + spacingY); break;
                    default: popups.get( i ).setY( popups.get( i ).getY() - height - spacingY);
                }
            }
        }