/* based on http://valums.com/vertical-scrolling-menu/ */
function makeScrollable(wrapper, scrollable){
	var wrapper = $(wrapper), scrollable = $(scrollable);
	wrapper.css({overflow: 'hidden'});						
	scrollable.slideDown("slow", function(){ enable(); });					
			
	
	function enable(){
		var inactiveMargin = 99;	
		var wrapperWidth = wrapper.width();
		var wrapperHeight = wrapper.height();
		var scrollableHeight = scrollable.outerHeight() + 2*inactiveMargin;

		var lastTarget;			
		wrapper.mousemove(function(e){
			lastTarget = e.target;
			var wrapperOffset = wrapper.offset();	
			var top = (e.pageY -  wrapperOffset.top) * (scrollableHeight - wrapperHeight) / wrapperHeight - inactiveMargin;
			if (top < 0) { top = 0; }			
			wrapper.scrollTop(top);
		});		
	}
}