function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImage(img_name,img_src) {
	if (document.images && (preloadFlag == true)) {
		document[img_name].src = "/images/button_" + img_src + ".jpg";
	}
}

//var preloadFlag = false;
var preloadFlag = true;
function preloadImages() {
	if (document.images) {
		buttonr_over = newImage("/images/button_r_on.jpg");
		buttonb_over = newImage("/images/button_b_on.jpg");
		buttong_over = newImage("/images/button_g_on.jpg");
		buttony_over = newImage("/images/button_y_on.jpg");
		preloadFlag = true;
	}
}