Another option is to pack the buttons into a Pane inside the main window. A benefit to this is you can make just a portion of the window scrollable if you should so desire.

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

my $top = MainWindow->new;

my $pane = $top->Scrolled('Pane',
    -scrollbars => 'e',
)->pack(-expand => 'y', -fill => 'both');

for (0 .. 9)
{
    $pane->Button(
        -text => $_,
        -width => 15,
        -command => [sub{print "Button $_[0] Pressed\n"},$_],
    )->pack;
}

$top->Button(
    -text => 'Quit',
    -command => sub{$top->destroy},
)->pack;

MainLoop;
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