function setMenuPositions(num,add)
{
	posY=160;

	largeur=(document.body.clientWidth > 780)?780:document.body.clientWidth;

	posX=Math.floor((largeur - 780) / 2) + add;

	document.getElementById('layer_menu_'+num).style.left=posX+'px';
	document.getElementById('layer_menu_'+num).style.top=posY+'px';
}

function showMenu(num,add)
{
	if(document.getElementById)
	{
		setMenuPositions(num,add);

		document.getElementById('layer_menu_'+num).style.visibility='visible';
	}
}

function hideMenu(num)
{
	if(document.getElementById)
	{
		document.getElementById('layer_menu_'+num).style.visibility='hidden';
	}
}