It would seem that the forward declaring of std:: classes is illegal c++.
This is done in vcl_complex_fwd.h.
>Reply-To: "John Biddiscombe" <jbiddiscombe@...>
>From: "John Biddiscombe" <jbiddiscombe@...>
>To: "Bill Hoffman" <bill.hoffman@...>
>Subject: Re: Borland + ITK
>Date: Thu, 22 Aug 2002 12:46:22 +0100
>X-Mailer: Microsoft Outlook Express 6.00.2600.0000
>A comment from another BCB user...
>Forward-declaring ::std components is not allowed in C++ [126.96.36.199/1]. Therefore, I would say that this is not a bug.