my %tk;
$tk{top}       =  MainWindow->new();
$tk{menubar}   =  $tk{top}->Menu;
$tk{top}->configure( -menu => $tk{menubar} );
$tk{menu_file} =  $tk{menubar}->cascade( -label => '~File' );
$tk{menu_exit} =  $tk{menubar}->command( -label => '~Exit', -command => sub { Tk::exit(0); } );