Just from looking at my Tk test scripts, you should look at Tk::DynaTabFrame or look at the script below, where you may be able to switch tab titles, by examing the following, and doing some juggling. :-)

#!/usr/bin/perl
use Tk;
use Tk::NoteBook;
use Tk::Photo;
use Tk::Compound;
use strict;

my $mw=tkinit;
my @tabs = qw/One Two Three/;
my $nb=$mw->NoteBook(
       -font => "Arial 24",  
       -background=>'lightgreen',
       -inactivebackground => "lightgray",
       -tabpadx => 5,
       -tabpady => 5,
      )->pack;

my $c = $mw->Compound(-foreground=>'black',-bg=>'red',-showbackground=
+>1);
$c->Text(-text => "Four", -font => "Arial 24");

foreach my $title (@tabs){
 $nb->add($title,-label=>$title);
}
$nb->add("Four",-image => $c);

my $id = $mw->repeat(500,sub{&chgtab($tabs[3])});
$nb->bind('<ButtonRelease-1>', [\&killtimer,Ev('x'),Ev('y')]);
 
MainLoop;
 
sub killtimer{
   my ($w,$x,$y) = @_;
   my $tab = $w->identify($x,$y);
   if ($tab eq "Four"){
      $nb->pageconfigure($tab,-label=>$tab);
      $c->configure(showbackground=>0);
      $id->cancel;
   }

}

sub chgtab {
   $c->configure(-showbackground=>!$c->cget(-showbackground));
}
[download]

Zentara, thanks. But it appears to me your solution is using the Tk interface rather than the Tkx, so my question is which do you like better and why? I did start with the Tk interface and moved to the Tkx because having the latest Tcl/Tk engines. Not to mention that the GUI had the themed widgets which of course looks more current on WINDOWS. But, I am beginning to re-think my decision... any advice?