function Rollovers_swap(id){ // id to swap in an image, null to swap out
  if (id != null)
	{	
		var image = document.images[id]
		if (image == null) return
	
		var newimage = this.images[id]
		if (newimage == null) return
		
		this.temp_img = image
		this.temp_src = image.src
		
		image.src = newimage.src
	}
	else
	{
		if ((this.temp_img != null) && (this.temp_src != null))
			this.temp_img.src = this.temp_src
			
		this.temp_img = null
		this.temp_src = null
	}
}
	
function Rollovers(image_list){
	this.images = new Object()		// Storage for swap-in images
	this.Install = Rollovers_Install
	this.swap = Rollovers_swap
	
	// Storage for the current swap-out image
	this.temp_img = null
	this.temp_src = null

	for (var i=0; i < image_list.length; i++) {
		var id = image_list[i][0]
		var src = image_list[i][1]
		
		var image = new Image()
		image.src = src
		this.images[id] = image
	}
}

function Rollovers_Install() {	// Should be called after page is loaded
	var _this = this
	var swap_out = function(){_this.swap(null);}

	var set = function (id){
		var image = document.images[id]
		if (image == null) return
		image.onmouseover = function(){_this.swap(id);}
		image.onmouseout = swap_out
	}
	
	for(var id in this.images) set(id);
}