Delphi FMX . Setfocus

Question

In a field validation (Tedit) at Delphi Firemonkey, how do I make the component (Tedit) not lose focus?

procedure TFrmPes1101C.EditTabDataNascimentoExit(Sender: TObject);
begin
  inherited;
  if DataInvalida(EditTabDataNascimento.Text) then
  begin
    ShowMessage('Data inválida.');
    EditTabDataNascimento.SetFocus;
  end;
end;

*Even with the date invalid, the cursor moves to the next field.