#!/usr/bin/perl

use strict;
use warnings;
use Tk;
use Tk::Pane;

my $mw = MainWindow->new();
$mw->geometry('500x500');

my $pane = $mw->Scrolled( 'Pane', -scrollbars => 'se' )->pack( -side => 'left', -fill => 'both', -expand => 1 );

foreach my $col ( 1 .. 1000 ) {

  # try swapping the values of $txt below
  # my $txt = $col;      # works
  my $txt = "Col $col";  # doesn't work

  # try swapping the geometry managers (same result)
  $pane->Label( -text => $txt, -relief => 'groove', -height => 20 )->grid( -row => 0, -column => $col );
  # $pane->Label( -text => $txt, -relief => 'groove', -height => 20 )->pack( -side => 'left' );
}

MainLoop;