Just to give one example of what Anonymous Monk have said:

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->Button(-text => "you are now on page 2")->pack;
my $page3 = $mw->add("page3", -label => "page3");
$page3->Entry(-width => 20)->pack;
my $page4 = $mw->add("page4", -label => "page4");
$page4->Button(-text => "you are now on page 4")->pack;

MainLoop;
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