function clickReturn () {
   var bAgent = window.navigator.userAgent;
   var bAppName = window.navigator.appName;
   if ((bAppName.indexOf("Explorer") >= 0) && (bAgent.indexOf("Mozilla/3")  >= 0) && (bAgent.indexOf("Mac") >= 0))
   return true; // dont follow link
   else return false; // dont follow link
}

function popup(x,y,w,h,url,title) {
   var pars = "width="+w+",height="+h+",left="+x+",top="+y+",resizable=yes,scrollbars=yes,location=yes";
   if ((typeof(F1) == "undefined") || (F1.closed)) {
      F1 = window.open(url,"Fenster1",pars);
   } else {
      F1.document.location.href=url;
   }
   F1.focus();
   return false;
}