win_array = []

function openWin(loc,winName,winWidth,winHeight,winParams){          // open popup window
   if (!win_array[winName]) win_array[winName] = null
   if (!win_array[winName] || (win_array[winName] && win_array[winName].closed)){
      if (winParams=='full'){
         winParams = 'resizable=yes,menubar=yes,status=yes,toolbar=yes,titlebar=yes,location=yes,directories=yes,scrollbars=yes'
      }
      win_array[winName] = window.open(loc,winName,"width="+winWidth+",height="+winHeight+","+winParams)
   }

   win_array[winName].location = loc
   win_array[winName].focus()   

}