function preloadImages() {
	if (document.images) {
		var imgFiles = preloadImages.arguments;
		var preloadArray = new Array();

		for (var i=0; i<imgFiles.length; i++) {
			preloadArray[i] = new Image();
			preloadArray[i].src = imgFiles[i];
		}
	}
}

function swapImage(img_id, url, lock) {
	var img = document.getElementById(img_id);

	if (img == null)
		return;

	if (img.locked == true)
		return;

	if (lock != true)
		img.oldSrc = img.src;
	else
		img.locked = true;

	img.src = url;
}

function restoreImage(img_id) {
	var img = document.getElementById(img_id);

	if (img.oldSrc)
		img.src = img.oldSrc;
}