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(); }