var ns4up = (document.layers)                                ? 1 : 0;
var ns6up = (document.getElementById&&!document.all)         ? 1 : 0;
var op5up = (navigator.userAgent.indexOf('Opera')>0&&!ns6up) ? 1 : 0;
var ie4up = (document.all && !op5up)                         ? 1 : 0;

//preload images:
kruk  = new Image(); kruk.src  = "navigatie/kruk.gif";
kruk2 = new Image(); kruk2.src = "navigatie/kruk2.gif";

function hiLite(imgDocID, imgObjName) {
  if (imgDocID != huidige) {
    if(ie4up || op5up) { document.all.slide1.document.images[imgDocID].src = eval(imgObjName + ".src") }
    else if(ns4up)     { document.slide1.document.images[imgDocID].src     = eval(imgObjName + ".src") }
    else if(ns6up)     { document.images[imgDocID].src                     = eval(imgObjName + ".src") }
  }
}

//  self.onError=null;

currentY    = 0;
lastScrollY = 0;
ETteller    = 0;

function heartBeat() {
  if(ie4up)       { diffY = document.body.scrollTop; }
  else            { diffY = self.pageYOffset; }
  if(diffY != lastScrollY) {
     percent = .03 * (diffY - lastScrollY);
     if(percent > 0) { percent = Math.ceil(percent); }
     else            { percent = Math.floor(percent);}
     if(ie4up || op5up) { document.all.slide1.style.pixelTop += percent;
  	          document.all.slide2.style.pixelTop += percent; }
     else if(ns4up)     { document.slide1.top                += percent;
  	          document.slide2.top                += percent; }
     else if(ns6up)     { document.getElementById('slide1').style.top = diffY + lastScrollY - diffY;
  	          document.getElementById('slide2').style.top = diffY + lastScrollY - diffY; }
     lastScrollY = lastScrollY + percent;
  }
}
if(ns4up || ie4up || op5up || ns6up) { action = window.setInterval("heartBeat()",50); }