public void restoreState() {
        content.append("Q").append_i(separator);
        int idx = stateList.size() - 1;
        if (idx < 0)
            throw new IllegalPdfSyntaxException(MessageLocalization.getComposedMessage("unbalanced.save.restore.state.operators"));
        state = stateList.get(idx);
        stateList.remove(idx);
    }