var arrow = new Array(), empty = new Array()
for (i=0; i<=6; i++) arrow[i] = new Image()
arrow[0].src = 'img/btn_abouton.gif'
arrow[1].src = 'img/btn_cenbumon.gif'
arrow[2].src = 'img/btn_krediton.gif'
arrow[3].src = 'img/btn_depoziton.gif'
arrow[4].src = 'img/btn_serviceon.gif'
arrow[5].src = 'img/btn_docon.gif'
arrow[6].src = 'img/btn_contactson.gif'

for (i=0; i<=6; i++) empty[i] = new Image()
empty[0].src = 'img/btn_aboutoff.gif'
empty[1].src = 'img/btn_cenbumoff.gif'
empty[2].src = 'img/btn_kreditoff.gif'
empty[3].src = 'img/btn_depozitoff.gif'
empty[4].src = 'img/btn_serviceoff.gif'
empty[5].src = 'img/btn_docoff.gif'
empty[6].src = 'img/btn_contactsoff.gif'

function toggleImg(n, activate) {
document.images['btn'+n].src=activate?arrow[n].src:empty[n].src
}

function openNewWin(url, name, scr, w, h)
{
var w1 = window.open(url, name, 'toolbar=no,location=no,status=no,menubar=no,resizable=no,directories=no,scrollbars=no,width='+w+',height='+h+'');
w1.focus();
}

<!--
dom = (document.getElementById) ? true : false;
nn4 = (document.layers) ? true : false;
ie = (document.all) ? true : false;

total_layers = 7;

function showEl( ) {
for(i=0;i<showEl.arguments.length;i++) {
if (ie) {document.all[showEl.arguments[i]].style.visibility = "visible";}
else if (nn4) {document.layers[showEl.arguments[i]].visibility = "show";if(document.layers['fllyr']){document.layers['fllyr'].visibility = "hide";};}
else {document.getElementById(showEl.arguments[i]).style.visibility = "visible";if(document.getElementById('fllyr')){document.getElementById('fllyr').style.visibility = "hidden";};}
}
}

function hideEl( ) {
for(i=0;i<hideEl.arguments.length;i++) {
if (ie) {document.all[hideEl.arguments[i]].style.visibility = "hidden";}
else if (nn4) {document.layers[hideEl.arguments[i]].visibility = "hide";if(document.layers['fllyr']){document.layers['fllyr'].visibility = "show";};}
else {document.getElementById(hideEl.arguments[i]).style.visibility = "hidden";if(document.getElementById('fllyr')){document.getElementById('fllyr').style.visibility = "visible";};}
}
}