my $TOP=Tk::MainWindow->new;
my $tp=$TOP->Toplevel;
$tmb=$tp->MenuButton(-text=>'',-tearoff=>0)->pack;
foreach my $d (@dir) 
{
 $tmb->command(-label=>decode('utf8',$d),-command=>sub
 {
  ...
 })
};

##</code><code>##

$tmb->configure(-menu=>'');