How to determine wich columnheader was clicked

In the forum I found sereval topics about how to determine the index of the column when a columnheader is clicked. But I did not found any answers that worked.
Does anybody know how to arrange this?

This seems to work fine for me:

var obj = new AW.Grid.Extended;
    obj.setColumnCount(4);
    obj.setRowCount(10);
    obj.setCellText(function(i, j){return j + "-" + i});
    obj.setHeaderText(["header 0","header 1","header 2","header 3"]);

    obj.onHeaderClicked = function(event, index, header){
        alert("Header clicked: " + index + " " + header);
    }; 

    document.write(obj);