How do I disable an AW.UI.Input box in a grid header? setAttribute("disabled","disabled") does not work.

I've got a grid, and in the grid I'm inserting a row of AW.UI.Input boxes in the header. I want to make some of them un-editable.

Here's the relevant piece of code:

for(var i = 0;i<10;i++){
    var textBox = new AW.UI.Input;
    if(i != 8){
        //disable all but i=8
        textBox.setAttribute("disabled","disabled");
    }
    grid.setHeaderTemplate(textBox,i,2);
}

I tried setAttribute("disabled","disabled") but that doesn't do it. I checked the class reference for AW.UI.Input and the Grid and I don't see anything like what I'm trying to do.

I might be able to use setCellEditable but they're in the Header, not in the actual table data section.

Any suggestions? Thanks,