The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.
#!/usr/local/bin/perl -w

use Tk;
use strict;
require Tk::Label;

my $fred = 'Something';

sub toggle
{
 use vars qw($callback);
 my $w = shift;
 my $r = $w->configure("-relief");
 $w->configure("-relief" => ($r eq "raised") ? "sunken" : "raised");
 $fred = reverse($fred);
 $callback = [\&toggle,$w] unless defined $callback;
 $w->after(1000,$callback);
}


my $top = MainWindow->new();


my $l   = $top->Label('-textvariable'=> \$fred);

$l->pack();

&toggle($l);

$top->update();

Tk::MainLoop();