window.onerror = null;
var netscape = 0;
var goodIE = 0;
browserName = navigator.appName.substring(0,8);
browserVer = parseFloat(navigator.appVersion);
if (browserName == "Netscape" && browserVer >= 3)
{ netscape = 1; }
if (browserName == "Microsof" && browserVer >= 4)
{ goodIE = 1; }

if (netscape || goodIE) {
names = new Array("blanco");
        buttons = new Array(4);
for (m=0; m<=3; m++) {
buttons[m] = new Image(); }
        buttons[0].src = "img/b_blanco.gif";
        buttons[1].src = "img/b_mapa1.gif";
        buttons[2].src = "img/b_contacto1.gif";
        buttons[3].src = "img/b_inicio1.gif";}

function swap(des,num) {
if (netscape || goodIE) {
document.images[names[des]].src = buttons[num].src;  }}