Your code is hard to read withall the regexes and everything, but this section is a real mess with Tk's eventloop,

 while (1)
        {
            ($nfound,$timeleft,@pending)= File::Tail::select(undef,und
+ef,undef,$timeout,@files);
        unless ($nfound)
        {
            print "Nothing to print \n"; 
        } 
        else 
        {
            foreach(@pending)
[download]

You should use Tk's internal fileevent to watch tail's output, and never use while(1) loops in an eventloop system, like Tk.

Here are a couple of Tk file tailing examples

#!/usr/bin/perl
use strict;
use Tk;
use IO::Handle;

my $H=IO::Handle->new;
open($H,"tail -f -n 50 z.txt |") or die $!;

my $main = MainWindow->new;

my $t = $main-> Scrolled('Text',
              -wrap=>'none')->pack(-expand=>1);

$main->fileevent(\*$H,'readable',[\&fill,$t]);

MainLoop;

sub fill {
  my ($w) = @_;
  my $text;
  my $text =<$H>;
  $w->insert('end',$text);
  $w->yview('end');
}
[download]

or

#!/usr/bin/perl
# tktail pathname
use warnings;
use strict;
use Tk;

my $pid = open(H, "tail -f -n 25 $ARGV[0]|") or die ;

my $mw = MainWindow->new;
my $t = $mw->Text(-width => 80, -height => 25, -wrap => 'none');
$t->pack(-expand => 1);
$mw->fileevent('H', 'readable', [\&fill_text_widget, $t]);
$mw->OnDestroy(\&quitCB);
MainLoop;

sub fill_text_widget {
my($widget) = @_;
my $text = <H>;
$widget->insert('end', $text);
$widget->yview('end');
} # end fill_text_widget


sub quitCB {
kill 9,$pid or die $!;
exit;
}
[download]