function addEvent(elm, evType, fn, useCapture)
// cross-browser event handling for IE5+, NS6+ and Mozilla/Gecko
// By Scott Andrew
{
if (elm.addEventListener) {
    elm.addEventListener(evType, fn, useCapture); 
    return true; 
    } else if (elm.attachEvent) {
    var r = elm.attachEvent('on' + evType, fn); 
    return r; 
    } else {
    elm['on' + evType] = fn;
    }
}