sub logout_button {
  my $self = shift;
  my $q = $self->query();
  my $output = "";

  $output .= $q->start_form( -name => 'logout' );
  $output .= $q->hidden(-name => 'authen_logout', -value => '1');
  $output .= $q->submit(-value => 'logout');
  $output .= $q->end_form();

  return $output;
}