function getEl(id){
	return document.getElementById(id);
}
function ver_submenu(str){
	getEl(str+'s').style.display = 'block';
}
function ocultar_submenu(str){
	getEl(str+'s').style.display = 'none';
}
function ocultar_otros(str){
	for(var i in arr)
		getEl('list_item_'+arr[i]).style.visibility = 'hidden';
	getEl(str).style.visibility = 'visible';
}
function mostrar_todos(){
	for(var i in arr)
		getEl('list_item_'+arr[i]).style.visibility = 'visible';
}
function pintar_a(id){
	getEl(id).style.backgroundImage='url(imagenes/list-item-sub-over.jpg)';
}
function despintar_a(id){
	getEl(id).style.backgroundImage='';
}