// rollOverImg
function RollOverImg(imgName, overSrc, bPreload){
	if(!document.images)return false;
	bPreload = bPreload == null ? true : bPreload; //default to true
	this.img = document.images[imgName];
	this.upSrc = this.img.src;
	this.overSrc = overSrc;
	if(bPreload){
		var preloadImg = new Image();
		preloadImg.src = this.overSrc;
	}
	var self = this;
	this.img.onmouseover = function(){self.over()}
	this.img.onmouseout = function(){self.up()}
	return(this)
}
RollOverImg.prototype.up = function(){
	this.img.src = this.upSrc;
}
RollOverImg.prototype.over = function(){
	this.img.src = this.overSrc;
}
//create multiple unnamed rollOverImg instances
function createRollOverImgSet(imgs, basePath){
	for(var args in imgs){
		args = imgs[args];
		new RollOverImg(args[0], basePath + args[1], args[2]);
	}
}