procedure TForm1.Button1Click(Sender: TObject);
begin
  Showmessage(inttostr(Edit1.SelStart));
end;

procedure TForm1.DBGrid1KeyUp(Sender: TObject; var Key: Word;
  Shift: TShiftState);
var
  i: word;
  c: TInplaceEdit;
begin
  for i := 0 to DBGrid1.ControlCount -1 do
  begin
    if DBGrid1.Controls[i] is TInPlaceEdit then
    begin
      c := DBGrid1.Controls[i] as TInPlaceEdit;
      Lable1.Caption := IntToStr(c.SelStart);
    end;
  end;
end;