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

my $mw  = tkinit;

$mw->fontCreate('big',
   -family=>'courier',
     -weight=>'bold',
       -size=>int(-18*18/14));

my $tx  = $mw->Text(
    -height     => 4, #initialy set it small
    -width  => 25,
    )->pack();


foreach (1 .. 20 ) { $tx->insert( 'end', "line$_\n" ); }
$tx->insert('end', "Blah " x 10);

my $end = $tx->index('insert');  #get last line

$tx->configure(-height=>$end);

my $button = $mw->Button(-text=>'Reconfigure',
              -command=>sub{
             
	          $tx->configure(-font => 'big');    
	          $tx->update;
		  $tx->configure(-height => $end);    
      	       
	      },

            )->pack();

MainLoop;