window.addEvent('domready', function() {

	var rightEl = $('right-col');
	var moveAmount = 44;
	var rightElHeight = rightEl.offsetHeight;
	var leftElHeight = 645;	// this is fixed
	
	$('down-arrow').addEvent('click', function(e){						 
			
		if (-(rightElHeight - leftElHeight) <= moveAmount - 144) {
		
			moveAmount -= 144;
			rightEl.tween('top', moveAmount);
			return false; // alternative syntax to stop the event
		}
	});

	$('up-arrow').addEvent('click', function(e){
			
		if (moveAmount + 144 <= 44) {
		
			moveAmount += 144;
			rightEl.tween('top', moveAmount);
			return false; // alternative syntax to stop the event
		}
	});
});