the example:
 
-------
use Win32::GUI;
 
my $mainWindow = new Win32::GUI::Window (
    -name     => "mainWindow",
    -title    => "Testing",
    -pos      => [0, 0],
    -size     => [300, 300],
);
 
my $lb=$mainWindow->AddListbox (
   -name   => "Listbox",
   -pos      => [20, 60],
   -size     => [100, 120],
   -multisel => 2,
    );
$mainWindow->Listbox->Add('One','Two','Three','Four'); 
$mainWindow->Listbox->Hide;
 
my $show=$mainWindow->AddButton (
   -name   => "Button",
   -pos      => [20, 20],
   -size     => [40, 40],
   -text     => 'Show',
   -onClick => \&Show,
    );
 
my $hide=$mainWindow->AddButton (
   -name   => "Button2",
   -pos      => [60, 20],
   -size     => [40, 40],
   -text     => 'Hide',
   -onClick => sub {$mainWindow->Listbox->Hide;},
    );
   
$mainWindow->Show;
 
Win32::GUI::Dialog();
 
sub Show {
  #select the first and last items
  $mainWindow->Listbox->Show;
  $mainWindow->Listbox->SetSel(0,1);
  $mainWindow->Listbox->SetSel(1,0);
  $mainWindow->Listbox->SetSel(2,0);
  $mainWindow->Listbox->SetSel(3,1);
  return 1;
}