var browserOK = false;

browserOK = true;
nav01=new Image(); nav01.src="images/logo_wat.gif";nav02=new Image(); nav02.src="images/logo_wat.gif";
nav11=new Image(); nav11.src="images/m_wir.gif";nav12=new Image(); nav12.src="images/m_wir2.gif";
nav21=new Image(); nav21.src="images/m_dienstleistungen.gif";nav22=new Image(); nav22.src="images/m_dienstleistungen2.gif";
nav31=new Image(); nav31.src="images/m_aktuell.gif";nav32=new Image(); nav32.src="images/m_aktuell2.gif";
nav41=new Image(); nav41.src="images/m_buero.gif";nav42=new Image(); nav42.src="images/m_buero2.gif";
nav51=new Image(); nav51.src="images/m_kontakt.gif";nav52=new Image(); nav52.src="images/m_kontakt2.gif";

bild11=new Image(); bild11.src="images/i_wir2.jpg";bild12=new Image(); bild12.src="images/i_wir1.jpg";
bild21=new Image(); bild21.src="images/i_dienst2.jpg";bild22=new Image(); bild22.src="images/i_dienst1.jpg";
bild31=new Image(); bild31.src="images/i_aktuell2.jpg";bild32=new Image(); bild32.src="images/i_aktuell1.jpg";
bild41=new Image(); bild41.src="images/i_buero2.jpg";bild42=new Image(); bild42.src="images/i_buero1.jpg";
bild51=new Image(); bild51.src="images/i_kontakt2.jpg";bild52=new Image(); bild52.src="images/i_kontakt1.jpg";



function bw(ok) {



 if (browserOK) {
  f = eval(r + "1.src");
  document [r].src = f;
  f = eval(ok + "2.src");
  document [ok].src = f
      r = ok
 }
}

function active(imgName, bildName){
        if (imgName != r)  {
        img1 = eval(imgName + "2.src");
        document[imgName].src = img1;
        }
                if (bildName != r)  {
        img1 = eval(bildName + "2.src");
        document[bildName].src = img1;
        }}

function inactive(imgName, bildName){
        if (imgName!=r)  {
        img2 = eval(imgName + "1.src");
        document [imgName].src = img2;
       }
       if (bildName!=r)  {
        img2 = eval(bildName + "1.src");
        document [bildName].src = img2;
       }}


function openWindow(url, traits){
newWindow=window.open(url,"displayWindow",traits);
//setFocus()
}

<!--  auskommentieren
      if (((navigator.appName == "Netscape") && (parseInt(navigator.appVersion.substring(0,1)) >=3))
      || ((navigator.appName == "Microsoft Internet  Explorer")&&(parseInt(navigator.appVersion.substring(0,1)) >=4)))
      {var version=true}