[ecfisa]

Hola.

A ver si así hace mas o menos lo que buscas...

Código Delphi [-]
   ...
   private
     procedure MMouseEvent(var Msg: TMsg; var Handled: Boolean);
   end;
...
implementation

procedure TForm1.FormCreate(Sender: TObject);
begin
  Application.OnMessage := MMouseEvent;
end;

procedure TForm1.MMouseEvent(var Msg: TMsg; var Handled: Boolean);
var
  P: TPoint;
begin
  P:= ScreenToClient(Mouse.CursorPos);
  if PtInRect(DBGrid1.BoundsRect,P) then
  begin
    if P.X = DBGrid1.Left + GetSystemMetrics(SM_CXVSCROLL) then
      SendMessage(DBGrid1.Handle, WM_HSCROLL, SB_LINELEFT, 0);
    if P.X = DBGrid1.Left+DBGrid1.Width - GetSystemMetrics(SM_CXVSCROLL) then
      SendMessage(DBGrid1.Handle, WM_HSCROLL, SB_LINERIGHT, 0);
  end;
end;
...

Saludos.