function ouvrir(l,h,s,url) { 
hauteur=Math.round((screen.availHeight-h)/2);
largeur=Math.round((screen.availWidth-l)/2);
window.open(url, "site", "toolbar=0,location=0,directories=0,status=0, scrollbars="+s+",resizable=0,menubar=0,top="+hauteur+",left="+largeur+",width="+l+",height="+h);
}