function popup_centree (ps_url, ps_nom, pi_largeur,pi_hauteur)
{
	li_left = (screen.width/2)-(pi_largeur/2);
	li_top = (screen.height/2)-(pi_hauteur/2);
	nw = window.open(ps_url, ps_nom, "scrollbars=yes,menubar=no,resizable=yes,left="+li_left+",top="+li_top+",width="+pi_largeur+",height="+pi_hauteur);
	nw.focus();
}