$mw->Button(-text => $_->[0], -command => $_->[1], -font => 24,
  )->pack( -side => 'left', -fill => 'x', -expand => 1) for
    [Restart => \&restart],
    ['Previous State' => \&previous],
    ['Random Move' => \&random],
    [Help => \&help],
    [Exit => sub {$mw->destroy}];