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) {
         contact_h = newImage("img/nav/contact_h.gif");
         over_h = newImage("img/nav/over_h.gif");
         jan_h = newImage("img/nav/jan_h.gif");
         producties_h = newImage("img/nav/producties_h.gif");
         preloadFlag = true;
     }
}

function toggle( targetId ){
  if (document.getElementById){
      target = document.getElementById( targetId );
        if (target.style.display == "none"){
          target.style.display = "";
        } else {
          target.style.display = "none";
        }
    }
}

window.onload = function(e) {
  preloadImages();
}