use strict;
use warnings;
use Tk;

my $name;
my $mw = MainWindow->new();
my $entry = $mw->Entry(
    -textvariable => \$name
    )->pack();

$mw->bind("<KeyRelease>" => sub {
    warn $_[0]->XEvent->k; 
});

$mw->MainLoop();
exit(0);