function validUrl(text, url){
    if (confirm(text))
      location.href = url;
  }

  function openUrl(url, width, height){
    var top  = (screen.height-height)/2;
    var left = (screen.width-width)/2;
    window.open(url, '', 'width=' + width + ', height=' + height + ', top=' + top + ', left=' + left + ', scrollbars=yes, resizable=no');
  }

  function empty(field){
    if ((field.value.length == 0) || (field.value == null))
      return true;
    else
      return false;
  }

  function checkEmail(email){
    if (email.value.indexOf("@") != "-1" && email.value.indexOf(".") != "-1" && email.value != "")
      return true;
    return false;
  }