print $q->scrolling_list(
  '-name'    => 'acct_num',
  '-values'  => [ sort { $clients{$a} cmp $clients{$b} } keys %clients ],
  '-labels'  => \%clients,
  '-default' => $default_value
);

##</code><code>##

print $q->scrolling_list(
  '-name'    => 'acct_nu',
  '-values'  => [ sort values %clients ],
  '-labels'  => { reverse %clients },
  '-default' => $default_value
);