function hideLevel(_levelId)
{
	var thisLevel = document.getElementById(_levelId );
	var thisImage = document.getElementById('img_'+_levelId);
	thisLevel.style.display = "none"; 
	//thisImage.src = "imagenes/icon_mas.jpg";
}
	
function showLevel(_levelId)
{
	var thisLevel = document.getElementById( _levelId );
	var thisImage = document.getElementById('img_'+_levelId);
	if (thisLevel.style.display == "none" || thisLevel.style.display == "")
	{
		thisLevel.style.display = "block";
		//thisImage.src = "imagenes/icon_menos.jpg";
	}
	else { hideLevel(_levelId); }	
}