#!/usr/bin/perl

# http://perlmonks.org/?node_id=1213205

use strict;
use warnings;
use Tk;
use Tk::ROText;

my $mw = MainWindow->new( -bg=> "#000000", -borderwidth=> 0); 
$mw->geometry( '1000x600' );

my $LB = $mw->Scrolled ( 'ROText',
            -bg => '#C0C0C0', 
            -fg => '#000000', 
            -selectforeground => '#000000', 
            -selectbackground => '#C0C0C0',
            -font => 'Courier 16 normal', 
            -relief => 'groove', 
            -cursor => 'top_left_arrow',
            -scrollbars => 'e',
        )->pack( -side => 'right', -expand => 1, -fill => 'both', );

sub selectAccount {
    my $this = shift;
    print "select: $this\n";
    $LB->tagConfigure("A$_", -background =>undef) for 1..200;
    $LB->tagConfigure("A$this", -background => 'yellow');
}
sub markAccount {
    my $this = shift;
    print "mark: $this\n";
    my $fontref = $LB->tagCget("A$this", -font);
    $LB->tagConfigure("A$this", -font => $fontref ? undef : 'Courier 1
+6 bold');
}
sub InitializeListBox {
    $LB->delete('1.0','end');
    for my $i (1..200) {
        $LB->insert('end', $i x 10, "A$i" );
        $LB->tag( 'bind', "A$i", '<Button-1>'  => sub { selectAccount(
+$i) } );
        $LB->tag( 'bind', "A$i", '<Double-1>'  => sub { markAccount($i
+) } );
        $LB->insert('end', "\n" );
     }
}

InitializeListBox();

MainLoop;
[download]

However, doing so on a tag without any -font option, it even even bypasses the whole IF-THEN-ELSE statement. Now, how do I reliably fetch a tag's "option" whether that option exists or not.

The answer to that is dot dot dot , same as the question :)

Ok, a better answer might be, first wake up, then first write simple program that runs and dot dot dot don't put stuff in your program until you understand it

Secondly, How do I delete a particular option/value within tag?

configure undef

Thirdly, Does it even matter if I delete unused options or not? Will having unused option slows down the script?

Does wearing a mustache slow you down? If you're sitting down?

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]