@Override
    public void addToModel(int idx, UsageNode element) {
      if (idx < getRowCount()) {
        insertRow(idx, element);
        cellSizesCache.addLine(idx);
      }
      else {
        addRow(element);
        cellSizesCache.addLine();
      }
    }
@Override
    public void addToModel(int idx, UsageNode element)