/* show-hide submenu */
function showSub(id) {
	var e = document.getElementById(id);
	var divHolder = document.getElementById("subMenuHolder");
	var hiddenHolder = document.getElementById("hiddenHolder");
	var child = divHolder.childNodes[0];

	if (child == null) {
		divHolder.appendChild(e);
	} else if (child.id != id) {
		divHolder.removeChild(child);
		hiddenHolder.appendChild(child);
		divHolder.appendChild(e);
	}
}