ListGrid scroll bar on IE11 with SmartGWT 4.0 and GWT 2.6.0

I spent a day trying to figure out what happened to the scrollbar on IE11, and no luck. The list grid displays all the results at once, but the scroll bar buttons do not work.

The SmartGWT showcase does not have this problem, and the funny thing is that I created a blank page with just a list there, and nothing else (without external CSS or JS), and yet .. I wonder what I am not doing at the end. Below is a screenshot of the error and the code used to generate the grid:

screenshot: http://s28.postimg.org/e34118br0/smart_gwt_ie11_bug.jpg

@Override
public void onModuleLoad() {
    RootPanel.get().add(newTestListGrid());
}

private ListGrid newTestListGrid() {
    ListGrid grid = new ListGrid();  
    grid.setWidth(550);
    grid.setHeight(224);
    grid.setZIndex(50000);
    grid.setHeaderHeight(40);
    List<ListGridField> fields = new ArrayList<ListGridField>();
    fields.add(new ListGridField("studentName", "Name"));
    grid.setFields(fields.toArray(new ListGridField[fields.size()]));
    List<ListGridRecord> records = new ArrayList<ListGridRecord>();
    ListGridRecord r;
    for (int oI = 0; oI < 100; oI++) {
        r = new ListGridRecord();
        r.setAttribute("studentName", "sei la");
        records.add(r);
    }
    grid.setData(records.toArray(new ListGridRecord[records.size()]));
    return grid;
}

OS: Windows 7 Browser: IE 11 SmartGWT: 4.0 GWT: 2.6.0

Does anyone know how to solve this?

Thanks so much for your time.