browserName = navigator.appName;
browserVer  = parseInt(navigator.appVersion);
var huidige_actief = '', huidige_over = '';

if ((browserName == "Netscape" && browserVer >= 3)
  || (browserName == "Microsoft Internet Explorer" && browserVer >= 4)) {
  browser = 1;
} 
else {
  browser = 0;
}
if (browser) {
  //loading the topbar navigation
  img03On  = new Image(); img03On.src  = "/images/nav/n03_on.gif";
  img03Off = new Image(); img03Off.src = "/images/nav/n03_off.gif";

  img07On  = new Image(); img07On.src  = "/images/nav/n07_on.gif";
  img07Off = new Image(); img07Off.src = "/images/nav/n07_off.gif";

  img12On  = new Image(); img12On.src  = "/images/nav/n12_on.gif";
  img12Off = new Image(); img12Off.src = "/images/nav/n12_off.gif";

  img14On  = new Image(); img14On.src  = "/images/nav/n14_on.gif";
  img14Off = new Image(); img14Off.src = "/images/nav/n14_off.gif";

  img18On  = new Image(); img18On.src  = "/images/nav/n18_on.gif";
  img18Off = new Image(); img18Off.src = "/images/nav/n18_off.gif";

  img99On  = new Image(); img99On.src  = "/images/nav/progress_adres_on.gif";
  img99Off = new Image(); img99Off.src = "/images/nav/progress_adres_off.gif";
}

function ImgOn(button) {
  if (browser) {
       if(huidige_over == button || huidige_actief == button) {
           return;
       }   
      
       if(huidige_over != '') {
           imgOn = eval(button + "On.src");
           document [button].src = imgOn;
       }
       
       huidige_over = button;
       imgOn = eval(button + "On.src");
       document [button].src = imgOn;
  }
}

function ImgOff(button) {
if (browser) {
      if(huidige_over != button || huidige_actief == button) {
          return;
      }
      else {
         imgOff = eval(button + "Off.src");
         document [button].src = imgOff;
         huidige_over = '';
      }
  }
}


function ImgClick(button) {
  if (browser) {
        if(huidige_actief == button) {
                return;
        }
       // de-actieveer vorige actieve button
        if(huidige_actief != '') {
                 imgOff = eval(huidige_actief + "Off.src");
                 document [huidige_actief ].src = imgOff;
        }
             // als de button 'over' was, dan nu niet meer
        if(huidige_over == button) {
                huidige_over = '';
        }
                 else {
                return;
                 }
        // zet button op actief
        huidige_actief = button;
                 imgCli = eval(button + "Cli.src");
         document [button].src = imgCli;
         }
}