use warnings;
use Glib qw{ TRUE FALSE };
use Gtk2 '-init';

my $builder;
my $window;

# get a new builder object
$builder = Gtk2::Builder->new();

$builder->add_from_file( "test.glade" )
    or die "Error loading GLADE file";
$window = $builder->get_object( "window1" )
    or die "Error while creating Main Window";
$liststore1 = $builder->get_object( "liststore1" );
$liststore1->set($liststore1->append,1, "12", 2, "12");
[download]

That's not using Tkx. I haven't played with Gtk enough to speak to it.