 
<!--
function open_window(votre_page)
{
var hauteur_popup=500;
var H = (screen.height - hauteur_popup) / 2;
var largeur_popup=800;
var L = (screen.width - largeur_popup) / 2;
pop_up = window.open(votre_page,"Popup","status=yes,scrollbars=yes,resizable=no,height="+hauteur_popup+",width="+largeur_popup+",top="+H+",left="+L);
}
-->