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

function changeImages() {
    if (document.images && (preloadFlag == true)) {
        for (var i=0; i<changeImages.arguments.length; i+=2) {
            document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
        }
    }
}

var preloadFlag = false;
function preloadImages() {
    if (document.images) {
        mt_home_over = newImage("images/mt_home-over.gif");
        mt_gruppo_over = newImage("images/mt_gruppo-over.gif");
        mt_valle_over = newImage("images/mt_valle-over.gif");
        mt_link_over = newImage("images/mt_link-over.gif");
        mt_contattaci_over = newImage("images/mt_contattaci-over.gif");
        preloadFlag = true;
    }
}

function ApriImmagine(NomeImg)
{
    open(NomeImg,'Immagini','titlebar=yes,scrollbars=yes,resizable=yes,height=500,width=550');
}