function showMainMenu(index) {
	var node = document.getElementById("menu_main_" + index);
	if (node != null ) document.getElementById("menu_main_" + index).style.visibility = "visible";
}

function hideMainMenu(index) {
	var node = document.getElementById("menu_main_" + index);
	if (node != null ) document.getElementById("menu_main_" + index).style.visibility = "hidden";
}