if (document.images) {
nexton = new Image();
nexton.src = "picts/next-on.gif"
nextoff = new Image();
nextoff.src = "picts/next-off.gif"
backon = new Image();
backon.src = "picts/back-on.gif"
backoff = new Image();
backoff.src = "picts/back-off.gif"}
function img_act(imgName) {
if (document.images) {
imgOn = eval(imgName + "on.src");
document [imgName].src = imgOn;}}
function img_inact(imgName) {
if (document.images) {
imgOff = eval(imgName + "off.src");
document [imgName].src = imgOff;}}