public void addChildAfter(TreeItem<Data> child, TreeItem<Data> after) {
    child.setParent(this);
    int idx = -1;
    for (int i = 0; i < myChildren.size(); i++) {
      TreeItem<Data> item = myChildren.get(i);
      if (item.equals(after)) {
        idx = i;
        break;
      }
    }
    if (idx == -1) {
      myChildren.add(child);
    } else {
      myChildren.add(idx, child);
    }
  }
public void addChildAfter(TreeItem<Data> child, TreeItem<Data> after)