function preload_images() {
	if (document.images) {
		if (!document.preloaded_images) {
			document.preloaded_images = [];
		}
		for (var i = 0; i < arguments.length; i++) {
			var img = new Image();
			img.src = arguments[i];
			document.preloaded_images.push(img);
		}
	}
}