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) {
        home_over = newImage("img/header/home_over.gif");
        fotos_over = newImage("img/header/fotos_over.gif");
        zine_over = newImage("img/header/zine_over.gif");
        links_over = newImage("img/header/links_over.gif");
        kontakt_over = newImage("img/header/kontakt_over.gif");
        about_over = newImage("img/header/about_over.gif");
        preloadFlag = true;
    }
}