Perl TK question

[spydermonkey]

I have a CMD script I'm rebuilding to work into Perl TK. One problem I am having is printing back to the UI itself. I know it has to be done within a label but I can't seem to get variables to print inside of one.<p>

Can someone show me how to make scalars (and other variables) work within a label? The code I have to date is

#!/usr/bin/perl

use strict;
use Tk;

my $mw = new MainWindow;
    $mw->geometry('150x200');
    my $menubar = $mw->Menu;
    my $file_menu = $menubar->cascade(-label => "~File");
    #$file_menu->command(-label => 'Exit',-command => \&do_this);
    my $edit_menu = $menubar->cascade(-label => "~Edit");
    my $help_menu = $menubar->cascade(-label => "~Help");
    $help_menu->command(-label => 'About..',-command => \&do_this);
    $mw->configure(-menu => $menubar);
MainLoop;

my $this = "that";
sub do_this
{
  $mw->Label(-text=>\$this)->pack;
}

Thank you!

 

[arn0ld]

#!/usr/bin/perl

use strict;
use Tk;
my $this = "that"; ## NOTHING beyond MainLoop is (directly) executed

my $mw = new MainWindow;
$mw->geometry('150x200');
my $menubar = $mw->Menu;
my $file_menu = $menubar->cascade(-label => "~File");
#$file_menu->command(-label => 'Exit',-command => \&do_this);
my $edit_menu = $menubar->cascade(-label => "~Edit");
my $help_menu = $menubar->cascade(-label => "~Help");
$help_menu->command(-label => 'About..',-command => \&do_this);
$mw->configure(-menu => $menubar);
MainLoop;

my $this = "that";
sub do_this
{
$mw->Label(-text=>$this)->pack; # NOT ref
}