function setClassForId(Id, Class) {

	if (document.getElementById) {
		TheBox = document.getElementById(Id);

		if (TheBox){
			TheBox.className = Class;
		}
	}

}

function switchMenu(subMenuId) {
	var prevDisplay = document.getElementById(subMenuId).className;
	var newDisplay = (prevDisplay == 'contentHidden') ? 'contentVisible' : 'contentHidden';
	setClassForId(subMenuId, newDisplay);
}