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("/images/home-over.gif");
		    mete_over = newImage("/images/turismo-over.gif");
		    hotels_over = newImage("/images/hotels-over.gif");
		    mappa_over = newImage("/images/strumenti-over.gif");
		    contatti_over = newImage("/images/contatti-over.gif");
		    preloadFlag = true;
	    }
    }