function show_announce() {

var ann_wd=600; var ann_ht=500;  // ширина и высота окна
var leftvar = (screen.width-ann_wd)/2;
var topvar = (screen.height-ann_ht)/2;
if (location.href.lastIndexOf('form.ru')+8 >= location.href.length) {

var par="width="+ann_wd+",height="+ann_ht+",left="+leftvar+",top="+topvar+",status=no,toolbar=no,menubar=no,location=no";

var wnd=window.open("/announce.php", "", "fullscreen=1, scrollbars=1");
//setTimeout(function() { wnd.close(); }, 8000); 
}
}