Sorry the command should have read

Um, thats not the only typo. No matter, here is some working code

#!/usr/bin/perl --
## perltidy -olq  -csc -csci=10 -cscl="sub : BEGIN END if " -otr -opr 
+-ce -nibc -i=4 -pt=0   "-nsak=*"
use strict;
use warnings;
use Data::Dump qw/ dd pp/;

$Tkx::TRACE = 64;
use Tkx;
use Tkx::FindBar;

my $name;
my $mw   = Tkx::widget->new( '.' );
my $text = $mw->new_text(
    -width  => 20,
    -height => 10,
);
foreach( qw/David Mary William/ ) {
    $text->insert( 'end', "$_\n" );
}

my $findbar = $mw->new_tkx_FindBar( -textwidget => $text, );

$mw->g_bind( '<Control-f>' => [ \&Tkx::FindBar::show,     $findbar ], 
+);
$mw->g_bind( '<F3>'        => [ \&Tkx::FindBar::next,     $findbar ], 
+);
$mw->g_bind( '<Shift-F3>'  => [ \&Tkx::FindBar::previous, $findbar ], 
+);
$mw->g_bind( '<Return>', \&fudge, );

$findbar->g_pack();
$text->g_pack();

$findbar->show();

Tkx::MainLoop();

sub fudge {
    dd( \@_ );
    dd [ $text->m_tag_configure( 'highlight' ) ];
    $name = $text->get( qw/highlight.first highlight.last/ );
    print "The name is $name\n";
    dd [ $text->tag( qw' ranges highlight' ) ];
    $text->m_tag_add( 'sel', qw/highlight.first highlight.last/ );
    $text->g_focus;    ## g_focus is g_focus not m_focus
    $findbar->hide;
} ## end sub fudge
[download]

Thank you that works perfectly