function open_window(pge)
{
	var hauteur_popup=400;
	var H = (screen.height - hauteur_popup) / 2;
	var largeur_popup=400;
	var L = (screen.width - largeur_popup) / 2;
	pop_up = window.open(pge,"Popup","status=yes,scrollbars=yes,resizable=no,height="+hauteur_popup+",width="+largeur_popup+",top="+H+",left="+L);
}