Sample Code

    grid.SlickGrid gd = prepare();
    gd.init();

    gd.onHeaderCellRendered.subscribe((grid.EventData e, Map parm) {
      if ((new math.Random()).nextInt(10) > 5) {
        (parm['node'] as DivElement).appendHtml('');
      } else {
        (parm['node'] as DivElement).appendHtml('');
      }
      print(parm);
    });
    columns.forEach((grid.Column _) {
      _.minWidth = 60;
      _.maxWidth = 200;
    });
    gd.setColumns(columns);
    gd.invalidate();
    gd.render();
  }