function addEvent (elm, eventType, fn, useCapture) {

	 if (elm.addEventListener) {
	    elm.addEventListener (eventType, fn, useCapture);
	 }

	 else if (elm.attachEvent) {
	    elm.attachEvent ('on' + eventType, fn);
	 }

	 else {
	    elm['on' + eventType] = fn;
	 }
}