在MDI主窗体中如下代码:

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Function ClientWindowProc( wnd: HWND; msg: Cardinal; wparam, lparam: Integer ): Integer; stdcall;
Var
pUserdata: Pointer;
Begin
pUserdata:= Pointer( GetWindowLong( wnd, GWL_USERDATA ));
Case msg of
WM_NCCALCSIZE: Begin
If (GetWindowLong( wnd, GWL_STYLE ) and (WS_HSCROLL or WS_VSCROLL)) <> 0 Then
SetWindowLong( wnd, GWL_STYLE, GetWindowLong(wnd, GWL_STYLE) and not (WS_HSCROLL or WS_VSCROLL));
End;
End;
Result := CallWindowProc(pUserdata, wnd, msg, wparam, lparam );
end;


procedure TForm1.FormCreate(Sender: TObject);
begin
// ShowScrollBar(mainform.clienthandle, SB_BOTH, false );
If ClientHandle <> 0 Then Begin
If GetWindowLong( ClientHandle, GWL_USERDATA ) <> 0 Then Exit;
// 加上回调句柄
SetWindowLong( ClientHandle, GWL_USERDATA, SetWindowLong( ClientHandle, GWL_WNDPROC, integer( @ClientWindowProc)));
End;
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