I don't think that should be too hard, since the text widget's height and width options are in terms of lines and character width. If you say -height=>4, -width=>25, that is 4 lines and 25 characters.

I havn't tried a $mw configure yet, but as esserte said, you may run into an infinite feedback loop if you try to reconfigure the $text widget as the $mw is being resized. You might be able to work out a flag, that gets set when the $mw resize starts, and is unset on the Button-1 Release. Then do your $text resize after the $mw resize is finished.

But back to the point of pixel size -vs -character size, look at this script, you don't need to worry about pixels. I didn't adjust for line width, but all you would need to do is loop through each line, take it's 'length' then reconfigure your $text widget -width option to the max length.

P.S. I guess there would be some trouble if you went to a very small window size, and you needed to search for a font that would fit and still be legible. All systems don't have the same fonts installed, so that is another problem.

#!/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;
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