Como ocultar as barras de rolagem em um aplicativo MDI?

No fórum ClubeDelphi apareceu esta rotina para ocultar as barras de rolagem de um form MDI pai:

 1 type
 2   TForm1 = class(TForm)
 3     procedure FormCreate(Sender: TObject);
 4 ...
 5 
 6 implementation
 7 
 8 ...
 9 
10 function ClientWindowProc(wnd: HWND; Msg: Cardinal;
11   wParam, lParam: Integer): Integer; stdcall;
12 var
13   f: Pointer;
14 begin
15   f := Pointer(GetWindowLong(wnd, GWL_USERDATA));
16 
17   case Msg of
18     WM_NCCALCSIZE: begin
19 
20         if (GetWindowLong(wnd, GWL_STYLE) 
21           and (WS_HSCROLL or WS_VSCROLL)) <> 0 then
22 
23           SetWindowLong(wnd, GWL_STYLE, 
24             GetWindowLong(wnd, GWL_STYLE) and 
25             not (WS_HSCROLL or WS_VSCROLL));
26       end;
27   end;
28 
29   Result :=
30    CallWindowProc(f, wnd, Msg, wparam, lparam);
31 end;
32 
33 procedure TForm1.FormCreate(Sender: TObject);
34 begin
35   if ClientHandle <> 0 then begin
36 
37     if (not (GetWindowLong(ClientHandle,
38       GWL_USERDATA) <> 0)) then begin
39 
40       SetWindowLong(ClientHandle, GWL_USERDATA,
41         SetWindowLong(ClientHandle, GWL_WNDPROC,
42         Integer(@ClientWindowProc)));
43     end;
44   end;
45 
46   // ...
47 end;