#!/usr/bin/perl
use warnings;
use strict;
use Gtk2;

my $pid = fork();

die "Fork failed" unless defined $pid;

if ($pid) {
    Gtk2->init();
    print "Parent: Child pid is $pid\n";
}
else {

    # Child
    print "Child: My pid is $$\n";
    sleep(120);
    exit 0;
}

# Parent
my $window = Gtk2::Window->new('toplevel');
my $button = Gtk2::Button->new('Quit');

$button->signal_connect(
    clicked => sub {
        kill $pid;
        Gtk2->main_quit;
    }
);
$window->add($button);
$window->show_all;
Gtk2->main;