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

use Tk;

my $mw = 'Tk::MainWindow'->new;

my $states = [qw[ disabled normal ]];

my @buttons;
for my $i (0, 1) {
    $buttons[$i] = $mw->Button( -text    => "Start $states->[$i]",
                                -state   => $states->[$i],
                                -command => sub { warn "B$i" },
                              )->pack;
    $mw->Entry( -textvariable => \$states->[$i] )->pack;
}

$mw->Button( -text    => 'Apply',
             -command => sub {
                 blink($_, $states->[$_]) for 0, 1;
             } )->pack;

sub blink {
    my ($idx, $state) = @_;
    $buttons[$idx]->configure( -state => $state );
}

MainLoop();