Note, that just like all the other form elements, the
       value of a hidden field is "sticky".  If you want to
       replace a hidden field with some other values after the
       script has been called once you'll have to do it manually:

            $query->param('hidden_name','new','values','here');



##</code><code>##

sub bar
{
    my $self = shift ;
    my $q = $self->query() ;
    my $output = '' ;

    my $first_number = $q->param( 'first_number' ) ;
    $q->param( 'runmode', 'mode3' );

    $output .= $q->start_html( "Bar" ) ;
    $output .= $q->h2( 'I\'m webapp run mode number two.' ) ;
    $output .= $q->h2( 'You click me and I\'ll click you!' ) ;
    $output .= $q->start_form ;
    $output .= $q->h3( 'Gimme another number!' ) ;
    $output .= $q->textfield( -name => 'second_number' );
    $output .= $q->hidden( -name => 'first_number',
                           -value => $first_number );
    $output .= $q->hidden( -name => 'runmode', -value => 'mode3' );
    $output .= $q->submit();
    $output .= $q->end_form();
    $output .= $q->end_html();

    return $output;
}