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

my $mw = MainWindow -> new;

my $frameSetUp = $mw -> Frame() 
		-> pack(
			-side => 'top',
			-fill => "both",
			-expand => 1);

my $startLoopButton = $frameSetUp -> Button(
			-text => 'Start', 
			-command => \&startLoop
			)
				-> pack(
					-side => 'left',
					-ipadx => 10,
					-fill => "both",
					-expand => 0);

my $endLoopButton = $frameSetUp -> Button(
			-text => 'Abort', 
			-command => \&interruptLoop
			)
				-> pack(
					-side => 'left',
					-ipadx => 10,
					-fill => "both",
					-expand => 0);

my $quitProgramButton = $frameSetUp -> Button(
			-text => 'Quit', 
			-command => \&quitProgram
			)
				-> pack(
					-side => 'left',
					-ipadx => 10,
					-fill => "both",
					-expand => 0);
		
MainLoop;

sub startLoop
	{
		while (1)
			{
				sleep (2);
				print STDERR "startLoop: still sleeping\n";
				$mw -> update();
			}
	}

sub interruptLoop
	{
		#something to interrupt startLoop and return to MainLoop?
		print STDERR "I've been pressed\n";
		die "but startLoop keeps running...\n\n";
	}

sub quitProgram
	{
		exit;
	}

sub Tk::Error
	{
 		my ($widget,$error,@locations) = @_;
		print STDERR "ERROR: $error\n";
	}