It sounds like you have bit of misunderstanding as how those Tk::NoteBook tabs can be rendered. They follow flow layout. Here is a piece of demo:

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

my $m = new MainWindow();
my $mw = $m->NoteBook()->pack;
my $page1 = $mw->add("page1", -label => "page1");
$page1->Entry(-width => 10)->pack;
my $page2 = $mw->add("page2", -label => "page2");
$page2->Entry(-width => 15)->pack;
my $page3 = $mw->add("page3", -label => "page3");
$page3->Entry(-width => 20)->pack;
my $page4 = $mw->add("page4", -label => "page4");
$page4->Entry(-width => 25)->pack;

MainLoop;
[download]

BTW, it is quite unfortunate that, the author of the Tk::NoteBook module even does not have the courtesy to test his demo code in his document, and the demo code is obviously wrong.