use strict;
use warnings;
use Tk;
use feature qw(say);

my $lblText = "Search:";
my $searchText = "";
my $txtContent = "Perl/Tk is probably the most widely known GUI for Perl. It is a great interface used by thousands of people. I am writing this to teach those with no previous knowledge of any programming language or GUI interface. You should know some Perl (you don't need to be an expert, but you need to know some basic/intermediate Perl) before you read this also. Perl/Tk is a module, so it should be fairly easy to get. If you don't know how to install modules";
$txtContent .= reverse $txtContent;
$txtContent =~ s/ /\n/g;

# ponctuation not allowed
my $mw = new MainWindow(-title => "Search demo");
my $lbl = $mw -> Label(-text => $lblText)->pack();
my $search = $mw -> Entry(-textvariable => \$searchText,
					   -validate => "key",
					   -validatecommand => sub {$_[1] !~ /[;,.:!?]/},	
    				   -invalidcommand  => sub {$mw->bell})->pack();
my $textarea = $mw -> Frame() ->pack();
my $txt = $textarea -> Text(-width => 40, 
							-height => 10)->pack();
$txt->insert('end', $txtContent);

my $btnCheck = $mw ->Button(-text => "Check", 
        				  -command => sub {&check_text();})->pack();        				  
MainLoop;

sub check_text()
{
	return if (length $searchText == 0);
	
	say "Searching: ", $searchText;
	my $result = $txt->search(-nocase => $searchText, 'end');
	
	if (defined($result))
	{
		say "Found at pos: $result";
		$txt->see($result);
	}
	else
	{
		say "Not found!";
	}
}

__END__