Well to help you understand a bit better, whenever you run something that can take time, and/or hang, like a ping, you need to separate that code from the gui eventloop code. This is usually done thru IPC, forking, or threads. That keeps the gui responsive.

So here is a simpler example of it. This code forks off the ping command, thru a piped open ( see "perldoc perlipc"), and then allows the tk eventloop to read the filehandle thru fileevent ( which is similar to C's select ). The problem with using Net::Ping is that it dosn't allow you direct access to the filehandles involved, like a piped open does. Then you need the hack workaround.

Here is a simpler version of using fileevent, for you to see the basics.

#!/usr/bin/perl -w
use Tk;
use strict;

my $host = 'localhost';
my $mw = MainWindow->new;

my $t = $mw->Scrolled("Text",-width => 80, 
      -height => 25, -wrap => 'none')->pack(-expand => 1);

my $button = $mw->Button(-text => 'Execute',
            -command => \&ping_test)->pack;

MainLoop();

sub ping_test {

open (PINGTEST, "ping $host 2>&1 |") or die "can't fork: $!";

$mw->fileevent(\*PINGTEST, 'readable', [\&fill_text_widget,$t]);

$button->configure(-text => 'Stop',
        -command => sub{
              print "Close Filehandle\n";
              close PINGTEST;# or die "bad ping: $! S?";
              print "All done!\n";
        });
}

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