procedure TForm1.cxBarEditItem1Change(Sender: TObject);
begin
  if (cxBarEditItem1.EditValue <> Null) and cxBarEditItem1.EditValue then
    ShowMessage('Checked!')
  else
    ShowMessage('Not Checked! (or null)');
end;

// Скрыть
procedure TForm1.Button1Click(Sender: TObject);
begin
  cxBarEditItem1.Visible := ivNever;
end;

// Показать
procedure TForm1.Button2Click(Sender: TObject);
begin
  cxBarEditItem1.Visible := ivAlways;
end;