///////////////// FONCTION GESTION D'AFFICHAGE DES LAYERS //////////////////////////////////

function showLay(num)
{
 for (i=1; i<=nbLay; i++)
 {
	eval("document.getElementById('nav" + i + "').style.visibility = 'hidden'");
 }
	eval("document.getElementById('nav" + num + "').style.visibility = 'visible'");
}

function hideLay(num)
{
	eval("document.getElementById('nav" + num + "').style.visibility = 'hidden'");
}





///////////////// FONCTION GESTION DU POSITIONNEMENT DES LAYERS //////////////////////////////////

var IE4 = (document.all && !document.getElementById) ? true : false;
var dom = (document.getElementById) ? true : false;
var NS4 = (document.layers) ? true : false;

/**** fonctions generiques ****/

function lib_getRealTop(imgElem) 
{
	yPos = eval('document.images["'+imgElem+'"]').offsetTop;
	tempEl = eval("document.images['"+imgElem+"']").offsetParent;
	while (tempEl != null)
	{
		yPos += tempEl.offsetTop;
		tempEl = tempEl.offsetParent;
	}
	return yPos;
}

function lib_getImageYfromTop(imgID) {
 if (NS4) return eval("document."+imgID).y;
 if (IE4) return lib_getRealTop(imgID);
 if (dom) return lib_getRealTop(imgID);

}

function lib_getRealLeft(imgElem)
{
	xPos = eval('document.images["'+imgElem+'"]').offsetLeft;
	tempEl = eval("document.images['"+imgElem+"']").offsetParent;
	while (tempEl != null)
	{
		xPos += tempEl.offsetLeft;
		tempEl = tempEl.offsetParent;
	}
	return xPos;
}


function lib_getImageXfromLEFT(imgID) {
 if (NS4) return eval("document."+imgID).x;
 if (IE4) return lib_getRealLeft(imgID);
 if (dom) return lib_getRealLeft(imgID);

}