For most Tk widgets, you should use the Scrolled method, which automatically adds scrollbars correctly. The only time you try to manually add a yscrollcommand is to do something tricky with the scrollbar.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = MainWindow->new;
$mw->title("Listbox");

# For example purposes, we will use one word for each letter
my @choices = qw/alpha beta charlie delta echo foxtrot golf hotel
india juliet kilo lima motel nancy oscar papa quebec radio sierra
tango uniform victor whiskey xray yankee zulu/;

#Create the text box and insert the list of choices in to it
my $lb = $mw->Scrolled("Listbox", 
       -scrollbars => "osoe",
       -height => 10,
       -width => 10,
       -selectmode => "multiple");

my $real_lb = $lb->Subwidget('scrolled');
$real_lb->configure(-borderwidth=>0);
$lb->insert("end", sort @choices);
$lb->pack(-side => "left");


$mw->Button(-text => "Exit",
             -command => sub{exit; })->pack(-side => "bottom");

$mw->Button(-text=>"View", 
             -command => sub {
         foreach ($lb->curselection()) {
                        print "$choices[$_]\n";
                }
      my $w = $real_lb->width;
      print "$w\n";
      my $sample = ' ' x 10;
      my $font_len = $lb->fontMeasure('default', $sample );         
      print "$font_len\n";     


     }
    )->pack(-side => "bottom");


$lb->selectionSet('end');
$lb->see('end');
MainLoop;
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