function openOverlayDiv(width, height) {
	//calculate the top and left position of the overlaydiv.
	if (/MSIE (\d+\.\d+);/.test(navigator.userAgent)) {
		calculateLeft = (Math.round(document.body.clientWidth/2) - (width/2));
		calculateTop  = 20;
		var screenHeight = document.body.clientHeight;
	} else {
		calculateLeft = (Math.round(window.innerWidth/2) - (width/2));
		calculateTop = 20;
		var screenHeight = document.body.clientHeight;
	}
	//load the things needed for the overlay
	var scrolled  	= GetScrollTop();
	var greyDiv 	= document.getElementById('greyOverlay');
	var overlayDiv 	= document.getElementById('bigImage');
	//grey overlay first
	greyDiv.style.position = 'absolute';
	greyDiv.style.left = '0px';
	greyDiv.style.top = scrolled+'px';
	greyDiv.style.visibility = 'visible';
	greyDiv.style.width = '100%';
	//the calculation of the height is something different, if the site is bigger than the screen, overlay that one
	var siteHeight = document.getElementById('site').offsetHeight;
	if (siteHeight < screenHeight) {
		greyDiv.style.height = '100%';
	} else {
		greyDiv.style.height = (siteHeight+20)+'px';
	}
	//the grey div is loaded, now we need the overlaydiv
	overlayDiv.style.visibility = 'visible';
	overlayDiv.style.width = width+'px';
	overlayDiv.style.height = height+'px';
	overlayDiv.style.position = 'absolute';
	overlayDiv.style.top = (calculateTop+scrolled)+"px";
	overlayDiv.style.left = calculateLeft+"px";
	//both div's are loaded, thank you
	return true;
}
function GetScrollTop() {
  return window.pageYOffset||
    document.documentElement&&document.documentElement.scrollTop||
    document.body.scrollTop||0;
}
function closeImageDiv() {
	var greyDiv 	= document.getElementById('greyOverlay');
	var overlayDiv 	= document.getElementById('bigImage');
	//overlay first
	overlayDiv.style.height = '0px';
	overlayDiv.style.width = '0px';
	overlayDiv.style.visibility = 'hidden';
	overlayDiv.innerHTML = '';
	//grey second
	greyDiv.style.height = '0px';
	greyDiv.style.width = '0px';
	greyDiv.style.visibility = 'hidden';
	greyDiv.innerHTML = '';
	return true;
}