The problem with this approach 

my $f =  $LB->tagCget("A$this", -font);
    printf "Mark: %d,%s\n",$this, $f;
    if (${$f} =~ /normal/i) {

[download]

When there is no font, then $f is not a reference, so program should first check if there is a reference

But the real problem, why modify tag options when should be adding/removing tags? markAccount should toggle a 'markAccount' tag for ALine

update:

On every double click, toggle bolded for A1 

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

use Tk;
use Data::Dump qw/ dd /;

my $mw = Tk::MainWindow->new;
$mw->geometry('400x300');


my $tw = $mw->Text(-wrap=>'word')->pack(qw/ -expand 1 -fill both /);
$tw->insert(
    'end',
    q{"There must be some kind of way out of here," Said the joker to 
+the thief.},
    'A1',
);

$tw->tag( 'bind', 'A1', '<Double-1>', \&AnDouble );
$tw->tagConfigure( 'bolded', -font => 'courier 18 bold' );
MainLoop;
sub AnDouble {
#~     my( $tw ) = @_;
#~     my $tw = $Tk::widget;
    my $tw = $Tk::event->W;
    my $mouseIndex = $tw->index( sprintf '@%s,%s',$Tk::event->x , $Tk:
+:event->y ) ;
    my @tags = $tw->tagNames( $tw->index('A1.first') );
    dd( [ $mouseIndex => @tags ], map { [ $_ => $tw->tagRanges($_) ] }
+ $tw->tagNames  );
    if( grep /bolded/, @tags ){
        $tw->tagRemove('bolded', $tw->tagRanges('A1') );
    } else {
        $tw->tagAdd('bolded', 'A1.first','A1.last' );
    }
}

__END__
$ perl tk-text-toggle-tagadd.pl
([1.9, "A1"], ["sel"], ["A1", "1.0", 1.74], ["bolded"])
(
  [1.4, "A1", "bolded"],
  ["sel", 1.1, 1.11],
  ["A1", "1.0", 1.74],
  ["bolded", "1.0", 1.74],
)

[download]

In reply to Re: How to extract, delete TK tags' option/value (Tk ROText indices index tagAdd tagRemove) by Anonymous Monk
in thread How to extract, delete TK tags' option/value by jsteng

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