var WindowObjectReference = null; // global variable
      function openWindow(url, help) {
                        
      if(WindowObjectReference == null || WindowObjectReference.closed)
           /* if the pointer to the window object in memory does not exist
              or if such pointer exists but the window was closed */
 
       {
         WindowObjectReference = window.open(url, help, "width=500,height=750,top=100,left=390,alwaysRaised=yes,toolbar=0,directories=0,menubar=0,status=1,resizable=yes,location=0,scrollbars=1,copyhistory=0");
         WindowObjectReference.focus();

         /* then create it. The new window will be created and
            will be brought on top of any other window. */
       }
      else
       {
         WindowObjectReference.focus();
         WindowObjectReference = window.open(url, help, "width=500,height=750,top=100,left=390,alwaysRaised=yes,toolbar=0,directories=0,menubar=0,status=1,resizable=yes,location=0,scrollbars=1,copyhistory=0");


         /* else the window reference must exist and the window
            is not closed; therefore, we can bring it back on top of any other
            window with the focus() method. There would be no need to re-create
            the window or to reload the referenced resource. */
      };
    }