function openPullDownMenu(item) {
	controllingNode = item.parentNode.parentNode;
	
	if (controllingNode.className=="open") {
		closePullDownMenu(item); // toggle state
	} else {
		// close whole menu before, else user could open multiple menus
		closeWholeMainMenu();
		controllingNode.className = "open";
	}
}

function closePullDownMenu(item) {
	controllingNode = item.parentNode.parentNode;
	controllingNode.className = "closed";
}

function closeWholeMainMenu() {
	menuNode = document.getElementById("menu");
	controllingNodes = menuNode.getElementsByTagName("dl");
	for (var i=0; i<controllingNodes.length; i++) {
		controllingNodes[i].className = "closed";
	}
}