function preloadImages() {
	if (document.images) {
		var home_off = new Image();
		home_off.src = "images/home_off.gif";
		var home_on = new Image();
		home_on.src = "images/home_on.gif";
		var leistungen_off = new Image();
		leistungen_off.src = "images/leistungen_off.gif";
		var leistungen_on = new Image();
		leistungen_on.src = "images/leistungen_on.gif";
		var referenzen_off = new Image();
		referenzen_off.src = "images/referenzen_off.gif";
		var referenzen_on = new Image();
		referenzen_on.src = "images/referenzen_on.gif";
		var kontakt_off = new Image();
		kontakt_off.src = "images/kontakt_off.gif";
		var kontakt_on = new Image();
		kontakt_on.src = "images/kontakt_on.gif";
	}
}

function changeon(strBildname) {
	if (document.images) {
	document.images[strBildname].src = "images/" + strBildname + "_on.gif"
	}
}

function changeoff(strBildname) {
	if (document.images) {
	document.images[strBildname].src = "images/" + strBildname + "_off.gif"
	}
}