type TForm1 = class(TForm) procedure wmGetMinMaxInfo(var Msg : TMessage); message wm_GetMinMaxInfo; procedure TForm1.wmGetMinMaxInfo(var Msg : TMessage); begin PMinMaxInfo(Msg.lParam)^.ptMinTrackSize.X := 600; PMinMaxInfo(Msg.lParam)^.ptMinTrackSize.Y := 350; end;