my %attributes = ( 'onChange' => 'displaydbfields(' . $n . ')',  
                   'id' =>  'coltype' . $n,                                    
                            );


my $v = popup_menu  (
                -name => 'type',
                -values => \@COLUMN_TYPES,
                -default => $col->{type},
                -attributes=> \%attributes,
              );