function popup (pUrl, pLargeur, pHauteur)
{
	var x, y;
	
	x = screen.width/2 - pLargeur/2;
	y = screen.height/2 - pHauteur/2;
	
	window.name = "principal";
	var fenetre = window.open(pUrl, "popup", "statusbar=0,toolbar=0,location=0,menubar=0,directories=0,resizable=0,scrollbars=1,width=" + pLargeur + ",height=" + pHauteur);
	fenetre.moveTo(x, y);
}