my $slist = Gtk3::SimpleList->new (
              'Text Field'    => 'text',
              'Markup Field'  => 'markup',
              'Int Field'     => 'int',
              'Double Field'  => 'double',
              'Bool Field'    => 'bool',
              'Scalar Field'  => 'scalar',
              'Pixbuf Field'  => 'pixbuf',
            ); 

##</code><code>##

# just displays the value in a scalar as 
# Perl would convert it to a string
Gtk3::SimpleList->add_column_type( 'a_scalar', 
        type     => 'Glib::Scalar',
        renderer => 'Gtk3::CellRendererText',
        attr     => sub {
             my ($treecol, $cell, $model, $iter, $col_num) = @_;
             my $info = $model->get ($iter, $col_num);
             $cell->set (text => $info);
        }
   );
 
# sums up the values in an array ref and displays 
# that in a text renderer
Gtk3::SimpleList->add_column_type( 'sum_of_array', 
        type     => 'Glib::Scalar',
        renderer => 'Gtk3::CellRendererText',
        attr     => sub {
             my ($treecol, $cell, $model, $iter, $col_num) = @_;
             my $sum = 0;
             my $info = $model->get ($iter, $col_num);
             foreach (@$info)
             {
                 $sum += $_;
             }
             $cell->set (text => $sum);
        } 
   );