DisableTextField = function() {
};

DisableTextField.add_method('exec',
  function (element, value) {
    try {
      if (value) {
        this.clear_value(element);
        this.disable_element(element);
      }
      else {
        this.enable_element(element);
      }
    }
    catch (error) {
      alert('DisableTextField Error: ' + error);
    }
    return true;
  }
);

DisableTextField.add_method('clear_value', function (element) {
  element.value = '';
}
);

DisableTextField.add_method('disable_element', function (element) {
  element.disabled = true;
  element.className = 'formdisabled';
}
);

DisableTextField.add_method('enable_element', function (element) {
  element.disabled = false;
  element.className = 'form';
}
);