Clicking in a checkbox column

Hi,

On a grid I have the first column as checkbox. I'm trying to catch the mouse shift-click on that cell to set a data in another cell. So I define the following property function:

obj.onCellShiftClicked = function(event, col, row) {
if (col != 0) {
return true;
}
this.setCellValue("Foo", 1, row);
}
But this function is not executed when I shift-click on a checkbox column.

After many trying I found that
the previous function is executed only if I define the following function:
obj.onCellValueChanged = function(value, col, row) {
return true;
}

Why?

Thanks,
Marco,
Milano Italy.

P.S. This is only an example, my real job is more complicated and I can't do the job in the
onCellValueChanged: I really need the execution of onCellShiftClicked.