SetWindowProc:: word or excel protected against it ?

Hi,

I am using the SETWINDOWPROC function using delphi 7 to trap the windows
Message and modify the WM_PAINT properties of any window form present. It's
works normaly with any current executed form, but when i try to use it to
trap an "excel" or "word" form, i have an error (not allowed). I think that
word, excel visio ... have a special protection against the SETWINDOWPROC !.

any idea to execute the setwindowproc with microsoft word, excel.... ???

Thank's a lot
Frank


(ps) my coding

type
  TWndProcSendMessage = procedure (UwndProc:TObject;
                               HandleWindow: HWND;
                               Msg :TMessage) of object;
  TUwndProc = class(tcomponent)
  private
     Handle:HWND;
     Etat:PEtat;
     FWndProcMessage : TWndProcMessage;
     procedure TrapWndMessages(var Msg :TMessage);
  public
     FWndProcSendMessage: TWndProcSendMessage;
     OldClientWP,NewClientWP : FARPROC ;
     constructor create(AOwner: TComponent); override;
     destructor Destroy; override;
  end;

  TFormCentral = class(TForm)
    .......


...................
...................
constructor TFormCentral.create.....
var ps:TUwndProc;
begin
             ps:=TUwndProc.create(self);
             ps.Handle:=CurrentFormHandle;
             ps.FWndProcSendMessage:=GestionProcedureWNDPROC;
             fp:=FARPROC(MakeObjectInstance(ps.TrapWndMessages));
             ps.NewClientWP:=fp;
             ps.OldClientWP:=FARPROC(SetWindowLong(fenetre,
GWL_WNDPROC,longint(fp)));
...............
end


procedure TUwndProc.TrapWndMessages(var Msg :TMessage);
var ThisHdc : HDC ;
    ha:hwnd;
    Fonction:TWndProcSendMessage;
begin

    Msg.Result := CallWindowProc(OldClientWP, self.Handle, Msg.Msg,
Msg.WParam, Msg.LParam);

    ha:=self.Handle;
    Fonction:=self.FWndProcSendMessage;

    case (Msg.Msg) of
        WM_ACTIVATE,WM_CLOSE:begin
           fonction(self,ha,msg);
        end;

        WM_PAINT,WM_SIZE:begin
           ThisHdc:=GetWindowDC(form1.Handle);
           BitBlt(ThisHdc, 4, 4, 18, 18, Image1.Canvas.handle, 0, 0,
SRCCOPY);
           releaseDC(form1.Handle,ThisHdc);
        end;
    end;

end;