TSMemo = class(TMemo)
procedure WM_HScroll(var Msg: TWMHScroll); message WM_HSCROLL;
procedure WM_VScroll(var Msg: TWMVScroll); message WM_VSCROLL;
end;
...
procedure TSMemo.WM_HScroll(var Msg: TWMHScroll);
begin
ShowMessage('HScroll');
end;
procedure TSMemo.WM_VScroll(var Msg: TWMVScroll);
begin
ShowMessage('VScroll');
end;
| 
Обнаружение прокрутки TMemo