Here's a version that allows shift-tab to go backwards properly, that is, it works both forward and backwards.

#!/usr/bin/perl

# https://perlmonks.org/?node_id=1226322

use strict;
use warnings;
use Tk;
require Tk::NoteBook;

my $main = MainWindow->new( );

my $nb = $main->NoteBook(-takefocus => 0 )->pack(-expand => 1, -fill =
+> 'both');

my $page1 = $nb->add('page1', -label => 'Page 1');

my $one = $page1->Entry()->pack();
$page1->Entry()->pack();
my $three = $page1->Entry()->pack();
$page1->Entry()->pack();

$three->bind('<Tab>' => sub { $main->after( 0, sub {$one->focus} ) } )
+;
$one->bind('<<LeftTab>>' => sub { $main->after( 0, sub {$three->focus}
+ ) } );

$nb->add('page2', -label => 'Page 2');

MainLoop;
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