use strict;
use warnings;
use Tk;

my $mw = tkinit;
my $s = 'text';
my $b = $mw->BrowseEntry->pack;
$mw->Button(-text => 'add entry',
            -command => sub{$b->insert('end',$s.='-foo');
                            $b->updateListWidth;
                        }
        )->pack;
MainLoop;