use strict;
use warnings;
use Tk ;
use Tk::ROText;
my $mw = tkinit();
my $lb = $mw->ROText->pack;
$lb->tag( 'configure', 'A1', 'background', 'red' );
print $lb->tag( 'cget', 'A1', 'background' ) , $/;
$lb->tag( 'configure', 'A1', 'background' , undef );
print  $lb->tag( 'cget', 'A1', 'background' ) , $/;
$lb->tag('configure', "A1", -font => 'courier 16 bold', );
print $lb->tagCget(qw' A1 font ') , $/;
$lb->tag('configure', "A1", -font => undef );
print $lb->tagCget(qw' A1 font ') , $/;
__END__
red

Tk::Font=SCALAR(0x106324c)