#!/usr/bin/perl -w

use Tk;

my $version = "1.0";

my $main = MainWindow->new();
$main->minsize( qw(250 250));
$main->title("Billing Mediation Platform");
$main->configure(-background=>'cadet blue');

my $menu_bar = $main->Frame(-relief=>'groove',
        -borderwidth => 3,
        -background  => 'dim grey',
        )->pack('-side'=>'top', -fill=>'x');

my $file_mb = $menu_bar->Menubutton(-text=>'File',
        -background => 'dim grey',
        -activebackground => 'light grey',
        -foreground => 'white',
        )->pack(-side => 'left');

$file_mb->command(label => 'Exit',    # the problem was here
        -activebackground => 'magenta',
        -command => sub{ $main -> destroy} );

$file_mb->separator();


MainLoop();