var winhandle = null;

function fktFoto(URL) {
  if ((winhandle != null) && (! winhandle.closed)) {
    winhandle.location.replace(URL);
  }
  else {
    winhandle=window.open(URL, 'imagewin', "width=840, height=820, resizable");
    winhandle.document.bgColor="#f1f1f1";
    winhandle.document.close();
  }
  winhandle.focus();
}