int y0 = getLocation().y;
  public int rowAtPoint(Point point)  {    if (point != null)      {        int y0 = getLocation().y;        int nrows = getRowCount();        int height = getRowHeight();        int y = point.y;        for (int i = 0; i < nrows; ++i)          {            if (0 <= y && y < height)              return i;            y -= height;          }      }    return -1;  }