The problem with using $mw->update or DoOneLoop() is that they still will block on slow network calls that are sluggish. When you use $lwp->get( $url), there is no place to insert the update, unless you use the more extended manual callback available in lwp, as shown in 
#!/usr/bin/perl -w
use strict;
use LWP::UserAgent;

# don't buffer the prints to make the status update
$| = 1;

my $ua = LWP::UserAgent->new();
my $received_size = 0;
my $url = 'http://www.cpan.org/authors/id/J/JG/JGOFF/parrot-0_0_7.tgz'
+;
print "Fetching $url\n";
my $request_time = time;
my $last_update = 0;
my $response = $ua->get($url,
                        ':content_cb'     => \&callback,
                        ':read_size_hint' => 8192,
                       );
print "\n";

sub callback {
  my ($data, $response, $protocol) = @_;

  my $total_size = $response->header('Content-Length') || 0;
  $received_size += length $data;

  my $time_now = time;

  # this to make the status only update once per second.
  return unless $time_now > $last_update or $received_size == $total_s
+ize;
  $last_update = $time_now;

  print "\rReceived $received_size bytes";
  printf " (%i%%)", (100/$total_size)*$received_size if $total_size;
  printf " %6.1f/bps", $received_size/(($time_now-$request_time)||1)
     if $received_size;
}

[download]
If you don't put your update calls into that callback, it will still block Tk until the get returns. And if the get() hangs, your Tk program could be hung forever, unless you set timers on it.

But it really is easier just to use a thread. :-)

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku

In reply to Re^5: Perl Tk freezes when command button is clicked ! by zentara
in thread Perl Tk freezes when command button is clicked ! by muralidharan

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.