test.cs

private void FlattenFormFields(ServerTextControl textControl) {
   int fieldCount = textControl.FormFields.Count;

   for (int i = 0; i < fieldCount; i++) {
      TextFieldCollectionBase.TextFieldEnumerator fieldEnum =
        textControl.FormFields.GetEnumerator();
      fieldEnum.MoveNext();

      FormField curField = (FormField)fieldEnum.Current;
      textControl.FormFields.Remove(curField, true);
   }
}