function prepareNavMenu()
{	
	//controleren of browser DOM ondersteunt en of dat juiste objecten in html zijn aangemaakt
	if(!document.getElementsByTagName) return false;
	if(!document.getElementById) return false;

	if(!document.getElementById("link1")) return false;
	if(!document.getElementById("link2")) return false;
	if(!document.getElementById("link3")) return false;

	// alle links zoeken
	var link1 = document.getElementById("link1");
	var link2 = document.getElementById("link2");
	var link3 = document.getElementById("link3");
	
	// src van de img tags toekennen aan variabele, gebruiken voor imageRollover
	var originalImageLink1 = link1.getElementsByTagName("img")[0].getAttribute("src");
	var originalImageLink2 = link2.getElementsByTagName("img")[0].getAttribute("src");
	var originalImageLink3 = link3.getElementsByTagName("img")[0].getAttribute("src");
	
	// behaviour koppelen aan de links
	link1.onmouseover = function()
	{
		slideShowStaticImageRollover(this);
	}

	link1.onmouseout = function()
	{	
		slideShowStaticImageRolloverOut(this, originalImageLink1);
	}
	
	link2.onmouseover = function()
	{
		slideShowStaticImageRollover(this);
	}
	
	link2.onmouseout = function()
	{	
		slideShowStaticImageRolloverOut(this, originalImageLink2);
	}
	
	link3.onmouseover = function()
	{
		slideShowStaticImageRollover(this);
	}

	link3.onmouseout = function()
	{
		slideShowStaticImageRolloverOut(this, originalImageLink3);
	}

}
addLoadEvent(prepareNavMenu);

function slideShowStaticImageRollover(object)
{
	if(!object.getAttribute("rel")) return false;
	if(!object.getElementsByTagName("img")) return false;
	var rolloverImage = object.getAttribute("rel");
	object.getElementsByTagName("img")[0].setAttribute("src",rolloverImage);
}

function slideShowStaticImageRolloverOut(object, previousImage)
{
	if(!object.getElementsByTagName("img")) return false;
	object.getElementsByTagName("img")[0].setAttribute("src",previousImage);
}