use strict;
use warnings;
use Tkx;

my $mw = Tkx::widget -> new ('.');
$mw -> g_wm_iconify;

my $Fkrs = $mw -> new_toplevel;

my $fac = '';

my $Ffac = $Fkrs -> new_entry (-textvariable => \$fac, -width => 8);
$Ffac -> g_grid (-row => 0, -column => 0, -sticky => 'ew');
$Ffac -> g_bind ('<Tab>', [\&fac, \$fac, \$Ffac, \$Fkrs]);

Tkx::update ();
while (Tkx::i::call('winfo', 'exists', $Fkrs)) {Tkx::i::DoOneEvent(0)};
Tkx::update ();
die "Normal end";

sub fac {
my ($p_fac, $p_Ffac, $p_Fkrs) = @_;
   if ($$p_fac =~ /^(?=.+)\d*(\.\d+)?$/) {

# I would like to use the break here!!;

      $$p_Fkrs -> g_destroy;
   } else {
      $$p_fac = '';
   }
}