#!/usr/bin/perl
use Tk;
$mw = MainWindow->new;
$l = $mw->Label(-text => "Test")->pack;
$f = $l->Frame;
$b = $mw->Button(-text => "Toggle visibility",
                 -command => sub {
                     if ($f->manager) {
                         $f->placeForget;
                     } else {
                         $f->place(-x => 0, -y => 0,
                                   -relwidth => 1,
                                   -relheight => 1,
                                  )
                     }
                 })->pack;
MainLoop;