// attach a handler to a particular event on an element

	// in a browser-independent way

	function registerEventHandler (element, event, handler) {

		if (element.attachEvent) {

			// MS registration model

			element.attachEvent('on' + event, handler);

		} else if (element.addEventListener) {

			// NN (W4C) regisration model

			element.addEventListener(event, handler, false);

		} else {

			// old regisration model as fall-back

			element[event] = handler;

		}

	}



	// get a delegate that refers to an instance method

	function getInstanceDelegate (obj, methodName) {

		return( function(e) {

			e = e || window.event;

			return obj[methodName](e);

		} );

	}