function showHideSub(toOpen, toClose) {
	if(toClose != '' && toClose != undefined) {
		var tmp_to_close = toClose.split(";");
		for(var i=0; i<=tmp_to_close.length; i++) {
			if(tmp_to_close[i] != '' && tmp_to_close[i] != null) {
				document[tmp_to_close[i]].src = '/images/werkenbijaltrecht-nl/navigation/'+tmp_to_close[i]+'.gif';
				document.getElementById('sub_nav_'+tmp_to_close[i]).style.visibility = 'hidden';
			}
		}
	}
	if (toOpen != '') { 
		document[toOpen].src= '/images/werkenbijaltrecht-nl/navigation/'+toOpen+'_over.gif'; 
		if(document.getElementById('sub_nav_'+toOpen)) {
			document.getElementById('sub_nav_'+toOpen).style.visibility = 'visible';
		}
	}
}