#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Tk::ActivityBar;

my $mw = MainWindow->new;

my $activity = $mw->ActivityBar(-anchor => 'w')->pack(-expand => 1);

$mw->Button(-text => 'Start Activity',
   -command => sub{ 
              $activity->startActivity(); #start the bar
              my $timer = $mw->after(6500,
	            sub{ $activity->configure('-value' => 0); } );
              &do_it;
	      })->pack();

$mw->Button(-text => 'Exit',
    -command =>sub{ exit })->pack();

MainLoop();

sub do_it{
  # you need to fork your command or it will block the gui
  # from functioning

  if(fork == 0){
    system("date; sleep 2; date; sleep 2; date; sleep 2");
  }
}