# statement is prepared in advance, and values are bound right after that

$mw->Busy;
$tk_col->delete(0, 'end');
$sth->execute(); # this blocks for several minutes;
$mw->Unbusy;
while (my $row = $sth->fetchrow_arrayref) {
    $tk_col->insert('end', $row);
}

##</code><code>##

POE::Session->Create (
   inline_states => {
      _start => \&execute_query(); # calls $kernel->yield('result') when done
      result => \&populate_result(); # fills Tk Widget
      _stop  => sub { $MW->update() };
   },
   args => [ $sth ],
);
POE::Kernel->run();