var amount = 2; // aantal submenu's

function hideMenu() {
	if (document.all) {
		for (i=1; i<=amount; i++) {
			document.getElementById("sub"+i).style.visibility = "hidden";
			document.getElementById("sub"+i).style.position = "absolute";
		}
	} else {
		for (i=1; i<=amount; i++) {
			document.getElementById("sub"+i).style.visibility = "collapse";
			document.getElementById("sub"+i).style.position = "absolute";
		}
	}
}

function showMenu(menuname) {
	hideMenu();
	if (document.all) {
		document.getElementById(menuname).style.position = "relative";
		document.getElementById(menuname).style.visibility = "visible";
	} else {
		document.getElementById(menuname).style.position = "relative";
		document.getElementById(menuname).style.visibility = "visible";
	}
}