TWebBrowser OnDocumentComplete event

i have a problem in OnDocumentComplete event of TWebbrowser ...
a message will pop up after the whole document(including multiple frames) is finished loaded ..(see attached code) ......

however, i accidentally found that it is not 100% working for certain website
e.g.  http://www.chatterboxgifts.co.uk/x11506.html

it is continue loading to another page even though the message "Complete document was loaded" did pop up..

is there anyway i can make sure that the whole HTML page is 100% finished loaded regardless of how many frames, or how the page is contructed ?

thanks

procedure YourForm.OnDocumentComplete(
  Sender: TObject;
  const pDisp: IDispatch;
  var URL: OleVariant);
var
  currentBrowser: IWebBrowser;
  topBrowser: IWebBrowser;
  document: OleVariant;
  windowName: string;
begin
  currentBrowser := pDisp as IWebBrowser;
  topBrowser := (Sender as TWebBrowser).DefaultInterface;
  if currentBrowser = topBrowser then
    ShowMessage('Complete document was loaded')
  else
  begin
    document := currentBrowser.Document;
    windowName := document.ParentWindow.Name;
    ShowMessage(Format('Frame "%s" was loaded', [windowName]));
  end;
end;