var MyNewWindow = "";

function popup(url, name, width, height, tool, loc, direct, stat, menu, scroll, resize){

   settings="toolbar="+tool+",location="+loc+",directories="+direct+",status="+stat+",menubar="+menu+",scrollbars="+scroll+",resizable="+resize+",width="+width+",height="+height;

   if (MyNewWindow.location && !MyNewWindow.closed)
   {
      MyNewWindow.close();
   }
   MyNewWindow = window.open(url,name,settings); 
}