The answer given is essentially correct. However, it is important to note that the problem is unrelated to $fn being or not being is lexical variable. The problem is simply that the sub being created (sub {&Load ($fn)}; why the ampersand?) says "pass Load the value of $fn". But that's the value when the sub is executed, not when it was defined!

The fix is to change that by making each iteration of the loop refer to a different lexical variable! But it still creates many subroutines and closures.

Perl/Tk provides another syntax for callbacks that is better in this case; see Tk::callbacks for the details.

Meanwhile, here's some sample code:

#!/usr/local/bin/perl -w

use strict;
use Tk;

my $mw = new Tk::MainWindow;
my $mb = $mw->Menubutton(-text => 'Test')->pack(-side => 'left');

sub Select {
  my $val = shift;
  my $top = $mw->Toplevel(-title => "Selection $val");
  $top->Button(-text => "Close Select($val)",
           -command => ['destroy', $top])->pack;
}

for(1..10) {
  $mb->command(-label => $_,
           -command => [\&Select, $_]);
}

MainLoop;
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Build your callbacks by giving a list reference of the sub and the arguments you'd like passed. So it's the same sub each time, and only a list of the arguments is stored.