function nop(ww,wh,url)
{
 var sw=screen.width;
 var sh=screen.height;
 if(!ww)ww=sw;if(!wh)wh=sh;
 var l=(sw-ww)/2;
 var t=(sh-wh)/2;
 window.open(url,"","width="+(ww)+",height="+(wh)+",top="+(t)+",left="+(l));
}