function show_menu(which){
	$valeur=(document.getElementById(which).style.visibility=='hidden'?'visible':'hidden');
	document.getElementById(which).style.visibility=$valeur;
}

function trigger_menu_item(id){
	elt=document.getElementById(id);
	if(elt.className=='category_hidden'){
		elt.className='category_visible';
	}
	else {
		elt.className='category_hidden';
	}
	return false;
}