my $handler = RequestHandler->new();
my $mw = tkinit();
$mw->Label(-text => 'Time: ')->pack(-side => 'left');

# Callbackfunktion
*time = sub {
    $handler->add_request( HTTP::Request->new('GET', 'http://bit.ly/2v7njgk'), '_time', sub {
        my $label = shift or return;
        $mw->Label(-textvariable => \$label )->pack(-side => 'left');
    } );
};

$handler->add_listener('_time', *time );


$mw->repeat(100 => sub { 
    $handler->listener(); 
    $mw->update(); 
});

MainLoop;