event – The browser Event object for the click event.
rowNum – the number of the row clicked on. This will be the number of the row in the working list, not the row within the grid (which may change with user sorting).
You can prevent the row being selected by returning false from this code.
The following will display an alert indicating the row clicked, and prevent row 3 from being selected:
alert("Row " + rowNum); return (rowNum != 3);