var preloadImageArray = new Array();

function pushImage(imageSrc){
	var image = new Image();
	image.src = imageSrc;
	preloadImageArray.push(image);
}

function swapBackground(obj){
	if(arguments[1] == null){
		obj.style.background = obj["tmp"];
	}
	else{
		obj["tmp"] = obj.style.background;
		obj.style.background = "url("+ arguments[1] +")";
	}
}