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

my ($mw, $lb1, $lb2);
my $count = 1;

$mw = MainWindow->new();

$lb1 = $mw->Listbox()->pack(-side => 'left');
$lb1->insert('end', 'insert','delete');
$lb1->bind('<<ListboxSelect>>' => \&sub1);
$lb2 = $mw->Listbox()->pack(-side => 'left');

MainLoop;
exit;

sub sub1 {
   my $sel = $lb1->curselection;
   if( $sel->[0] == 0 ) {
      &sub2;
   } else {
       &sub3;
   }
}

sub sub2 {
    $lb2->insert('end', "inserting $count");
    $count++;
}

sub sub3 {
    $lb2->delete('end');
    $count--;
}