how can I put combo boxes in a datagrid?

var myData = [
    ["cell1", "cell2", "cell3"],
    ["cell1", "cell2", "cell3"],
    ["cell1", "cell2", "cell3"]
];

var myItems = ["item11", "item12", "item13", "item14"];

var list = new AW.UI.List;
list.setItemText(myItems);
list.setItemCount(4);

var obj = new AW.UI.Grid;
obj.setCellData(myData);
obj.setColumnCount(3);
obj.setRowCount(3);

obj.setCellTemplate(new AW.Templates.Combo, 1);
obj.setPopupTemplate(list, 1);

document.write(obj);