var home_uit = new Image();
		var top_uit= new Image();
		var top_aan = new Image();
		var terug_uit= new Image();
		var terug_aan = new Image();
		
		top_uit.src="./images/top_uit.gif";
		top_aan.src="./images/top_aan.gif";
		terug_uit.src="./images/terug_uit.gif";
		terug_aan.src="./images/terug_aan.gif";
		
		function rolover(knop, s) {
			if(s == "aan"){
				document.images[knop].src= eval(knop + "_aan.src");
			}
			else if (s == "uit"){
				document.images[knop].src= eval(knop + "_uit.src");
			}
		}