var imagesLoaded = null;
var imgArray = new Array();
var itemID = "item_";                  ////////plaatjes heten item_[plaatje]
var onID = "_on";                        ////////mouseover/on plaatjes heten [plaatje]_on

// button object
////////////////////////////////////////////////////////////////////////
function Button(ref,srcon,srcoff){
 this.ref = ref; // reference to the image object
 this.srcon = srcon; // source of the mouseover image
 this.srcoff = srcoff; // source of the mouseout image
 // preloading mouseover
 this.imgObj = new Image();
 this.imgObj.src = srcon;
}

// preload function
/////////////////////////////////////////////////////////////////////
function preload(){
 var docImages = document.images;
 for (var i=0;i<docImages.length;i++) {
  if(docImages[i].src.indexOf(itemID) != -1 && docImages[i].src.indexOf(onID) == -1) {
   imgArray[docImages[i].name] = new
			Button(docImages[i],docImages[i].src.substring(0,docImages[i].src.length-4) +
			onID + docImages[i].src.substring(docImages[i].src.length-4),docImages[i].src);
  }
 }
 imagesLoaded = 1;
}

// highlight buttons
////////////////////////////////////////////////////////////////////
function imageOn(name){
 if(imagesLoaded){
  var obj = imgArray[name].ref;
  obj.src = imgArray[name].srcon;
 }
}

function imageOff(name){
 if(imagesLoaded){
  var obj = imgArray[name].ref;
  obj.src = imgArray[name].srcoff;
 }
}