public void writeExternal(Element element) {
    saveExpandedPaths();
    for (Map.Entry<String, TreeState> entry : myReadTreeState.entrySet()) {
      String subId = entry.getKey();
      TreeState treeState = entry.getValue();
      Element subPane = new Element(ELEMENT_SUB_PANE);
      if (subId != null) {
        subPane.setAttribute(ATTRIBUTE_SUB_ID, subId);
      }
      treeState.writeExternal(subPane);
      element.addContent(subPane);
    }
  }
public void writeExternal(Element element)