You might have better luck asking a more cogent question wherein you give sample code and more context such as what exactly you're trying to do. (Is this in a web page? Is this with Tk?) See How (Not) To Ask A Question.

(Likewise that's not a "buffer overflow"; that term's already got a completely different meaning and misusing it is only going to confuse things.)

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Tk::HList;

my $mw = new MainWindow;
my $hl = $mw->Scrolled(
    'HList',
    -scrollbars => 'osoe',
    -background => 'white',
    -columns    => 400,
    -header     => 1,
    -width      => 10,
    -height     => 5,
    -command => sub{ print "AAA\n"},
            )->pack(-fill=>'both',-expand=> 1);

my $bgcolor = "bisque";

foreach my $column ( 0 .. 399 ) {

## Create the Clickable Header
    my $b = $hl->Button(
        -background => $bgcolor,
        -anchor     => 'center',
        -text       => "Header$column",
        -command    => sub {
            print "You pressed Header $column\n";
        }
    );

    $hl->headerCreate(
        $column,
        -itemtype         => 'window',
        -borderwidth      => -2,
        -headerbackground => $bgcolor,
        -widget           => $b
    );

}


foreach my $num(1..10) {
     my $e = $hl->addchild(""); #will add at end

   foreach my $col(0..399){        
     $hl->itemCreate ($e, $col,
           -itemtype => 'text',
           -text => "$num-$col",
            );
     }
}

MainLoop;
[download]