It works fine on mine as well (ActiveState). Initializing the main window size may solve your problem. 

use strict;
use warnings;
use Tk;

my $mw = MainWindow->new();
$mw->geometry('100x300');
...

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In reply to Re: Tk Mainwindow resizing after child destroyed by hangon
in thread Tk Mainwindow resizing after child destroyed by g0n

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