function increase(img) {
    theobject = img;
    highlighting = setInterval("highlight(theobject)",30);
}
function decrease(img) {
    clearInterval(highlighting)
    if (img.style.mozopacity)
        img.style.mozopacity = 1.0;
    else if (img.filters)
        img.filters.alpha.opacity = 100;
}
function highlight(img) {
    if (img.style.mozopacity > 0.5)
        img.style.mozopacity = parseFloat(img.style.mozopacity) - 0.2;
    else if (img.filters && img.filters.alpha.opacity > 50)
        img.filters.alpha.opacity -= 20;
    else if (window.highlighting)
        clearInterval(highlighting);
}