#!/Perl/bin/perl

use strict;
use warnings;
use Tk;
use Tk::Scale;
use Tk::Balloon;
use Tk::NumEntryPlain;
use Tk::EntryCheck;
use Tk::NumEntry;

my $mw = Tk::MainWindow->new(-width=>150,-height=>150,);
$mw->gridPropagate(0);
$mw->packPropagate(0);

my $wert = 10;

my $e = $mw->NumEntry(
    -minvalue => 0,
    -maxvalue => 100,
);

my $s = $mw->Scale(
    -from => 0,
    -to => 100,
    -orient => 'horizontal',
);

my $l = $mw->Label(-textvariable=>\$wert,);

$e->configure(
    -validate => 'key',
    -vcmd => sub{ setScale($e, $s, $wert); },
);

$e->pack();
$s->pack();
$l->pack();

Tk::MainLoop;

sub setScale {
    my ($e, $s, $wert) = @_;
    my $zw = $e->get();
    if( $zw =~ m/.{0,0}/ ){
        print "Feld leer ($zw)!\n";
    }
}