#!perl

use strict;
use warnings;
use Tk;

my $mw = tkinit(-width => 400, -height => 300,);
$mw->packPropagate(0);

my $default_text = 'Default...';
my $previous_input = '';
my $e = $mw->Entry(-text => $default_text)->pack(-fill => 'x', -expand => 0);
my $e2 = $mw->Entry(-text => 'dummy',)->pack(-fill => 'both', -expand => 1);

$e->bind('<FocusIn>' => [sub{
        my $entry               = shift;
        my $default             = shift;
        my $previous    = shift;
        
        if( $entry->get() eq $default_text ) {
                $entry->delete(0, 'end');
                $$previous = '';
        }else{
                $$previous = $entry->get();
        }
        
}, $default_text, \$previous_input]);

$e->bind('<FocusOut>' => [sub{
        my $entry               = shift;
        my $default             = shift;
        my $previous    = shift;
        
        if( $entry->get() eq '' ) {
                $entry->insert(0, $default_text);
                $$previous = '';
        }else{
                $$previous = $entry->get();
        }
        
        print "previous input is now set to [$$previous]\n";
        
}, $default_text, \$previous_input]);

$e->bind('<Escape>' => [sub{
        my $entry               = shift;
        my $mw                  = shift;
        my $previous    = shift;

        if( $$previous ne '' and $entry->get() ne $previous_input ) {
                $entry->delete(0, 'end');
                $entry->insert(0, $$previous);
        }

        $mw->focus();
        
}, $mw, \$previous_input]);

$e->bind('<KeyPress>' => [sub{
        my $entry       = shift;
        my $key         = shift;
        
        return undef if $key eq 'Escape';
        
        print "$key was pressed\n";
        
}, Ev('K')]);

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