use Tk;
	 # The ActiveState compiler does better with "use Tk::Label".
     use Tk::Label;

     sub set_time() {
         ($sec, $min, $hour) = localtime(time);
         $label->configure(-text => sprintf(
              "The twenty-four hour time now is $hour:%02d:%02d.",
              $min, $sec));
     }

	 # Create a label as a place to display the time.
     $label = $MainWindow->new->Label();
	 # Put the label on-screen.
     $label->pack;
	 # Every half-second, update the current time in the label.
     $label->repeat(500, \&set_time);

     MainLoop;

Example 1: The myclock.pl script.