function fenetre(){

    var NewLargeurEcran = screen.availWidth;
    var NewHauteurEcran = screen.availHeight;

    window.open("http://www.aviva.fr/assurances/assurance/retraite-epargne/assurance-vie?typeProd=VEA&typePers=PP","Aviva","width=" + NewLargeurEcran + ",height=" + NewHauteurEcran + ",top=0,left=0");

}