determine what header row is clicked

if I use obj.setHeaderCount(2), and I click on the second header row,
how do I know that I clicked on the second row? Currently, it seems that all the header events only have column index parameters.

I feel like I am missing something simple here ;-)

in AW.Grid.Extended -

obj.onHeaderClicked = function(event, col, row){
    alert(row);
}