var myWindow

function testExist(URL)
{
  if (myWindow == null) {
	myWindow=window.open(URL, 'Win2','');
   return true;
  }
  if (myWindow.closed) {
    myWindow=window.open(URL, 'Win2','');
    return true;
  }
  return false;
}

function openWin(URL)
{
  if (!testExist(URL))  {
		myWindow.open(URL, 'Win2','');
	}
   myWindow.focus();
}