function roll(rub,etat)
{
if(etat==1)
	{
	document.getElementById("pianoff"+rub).style.visibility='hidden';
	document.getElementById("piano"+rub).style.visibility='visible';
	}
else if (etat==0)
	{
	document.getElementById("piano"+rub).style.visibility='hidden';
	document.getElementById("pianoff"+rub).style.visibility='visible';
	}
}