ktrl = 0;
ktrl2 = 0;

function fenster(datei)
{

   if(ktrl==0)
   {  mw = window.open(datei, "win1", "scrollbars=yes,width=640,height=600");
      mw.focus();
      ktrl = 1;
   }
   else
   {   if(mw.closed==true)
       {  mw = window.open(datei, "win1", "scrollbars=yes,width=640,height=600");
       }
       else 
         mw.location.href = datei;
       mw.focus();
   }
}

function fenster2(datei)
{

   if(ktrl2==0)
   {  mw = window.open(datei, "win2", "scrollbars=yes,width=640,height=600");
      mw.focus();
      ktrl2 = 1;
   }
   else
   {   if(mw.closed==true)
       {  mw = window.open(datei, "win2", "scrollbars=yes,width=640,height=600");
       }
       else 
         mw.location.href = datei;
       mw.focus();
   }
}

function fensterzu()
{  window.close()
}