#!/usr/bin/perl -w


# Libraries
use warnings;
use strict; 
use threads;
use threads::shared;
use Tk;
use Tk::Font;


# Shared variables
my $ltime : shared = 0;


# Globals
my $lbl_label = "Started";


# Main Program
my $thread = threads->create(\&worker_thread);
$thread->detach;

create_gui();


# Subroutines
sub worker_thread {
    while (1) {
        $ltime = localtime(time());
        print "Debug> In worker_thread():  Updated localtime to '$ltime'\n";
        sleep 60;
    }
}

sub create_gui {
    my $mw  = new MainWindow(-title => 'Thread example');
    my $fr  = $mw->Frame->pack(-expand => 1, -fill => 'both');
    my $fnt = $mw->Font(-family => 'arial', -size => '12');
    my $lbl = $fr->Label(-textvar => \$lbl_label, -background => '#ffefb5');
    my $btn = $fr->Button(-text => 'Exit (ESC)', -background => 'cyan');
    $btn->configure(-command => sub { exit }, -font => $fnt);
    $lbl->configure(-font => $fnt);
    $lbl->pack(-side => 'left');
    $btn->pack(-side => 'right');
    $mw->bind("<Escape>" => sub { $btn->invoke });
    $mw->repeat(1000 => \&update_gui);
    MainLoop;
}

sub update_gui {
    printf "Debug> In update_gui():  %s\n", time();
    $lbl_label = $ltime;
}