function addEvent(obj, evType, fn, useCapture) { 
if (obj.addEventListener) { 
 obj.addEventListener(evType, fn, useCapture); 
 return true; 
} else if (obj.attachEvent) { 
 var r = obj.attachEvent('on' + evType, fn); 
 return r; 
} else { 
 obj['on' + evType] = fn; 
} 
}