sub update_sample_data
 {
   my ($text_display, $text_data, $start_data, $end_data, $sheet, $nr, @headlines) = @_;
   my $display_text = $text_data->get("0.0", "end");
   $display_text =~ s/$start_data([^$end_data]+?)$end_data/$sheet->Range(&get_a1($nr, &array_index($1, @headlines)))->{Value}/sgei;     
   $text_display->delete("0.0", "end");
   $text_display->insert("end", $display_text);
 }


my $btn_show =    $combi_window->Button( -text => $start_data.' abc '.$end_data, -font => ['Tahoma', 8, 'bold'], -width => 7 );
$btn_show->configure ( -command => sub { &update_sample_data($text_display, $text_data, $start_data, $end_data, $sheet, $nr, @headlines); } );

&debug('init');
sub update_sample_data
 {
   my ($text_display, $text_data, $start_data, $end_data, $sheet, $nr, @headlines) = @_;
   my $display_text = $text_data->get("0.0", "end");

   &debug("display_text->isutf8 = ".(utf8::is_utf8($display_text) ? 1 : 0));
   &debug("start_data->isutf8 = ".(utf8::is_utf8($start_data) ? 1 : 0));
   &debug("end_data->isutf8 = ".(utf8::is_utf8($end_data) ? 1 : 0));
   &debug("display_text =\n$display_text");
   &debug("start_data= '$start_data'");
   &debug("end_data= '$end_data'");
   if ($display_text =~ /$start_data([^$end_data]+?)$end_data/si)
    {
     &debug('FOUND')
    }
   else
    {
     &debug("NOT FOUND")
    }

   $display_text =~ s/$start_data([^$end_data]+?)$end_data/$sheet->Range(&get_a1($nr, &array_index($1, @headlines)))->{Value}/sgei;
   $text_display->delete("0.0", "end");
   $text_display->insert("end", $display_text);
 }

sub update_sample_data
 {
   my ($text_display, $text_data, $start_data, $end_data, $sheet, $nr, @headlines) = @_;
   my $display_text = $text_data->get("0.0", "end");

   &debug("display_text->isutf8 = ".(utf8::is_utf8($display_text) ? 1 : 0));
   &debug("start_data->isutf8 = ".(utf8::is_utf8($start_data) ? 1 : 0));
   &debug("end_data->isutf8 = ".(utf8::is_utf8($end_data) ? 1 : 0));
   &debug("display_text =\n$display_text");
   &debug("start_data= '$start_data'");
   &debug("end_data= '$end_data'");
   if ($display_text =~ /$start_data([^$end_data]+?)$end_data/si)
    {
     &debug('FOUND')
    }
   else
    {
     &debug("NOT FOUND")
    }
   my $test = '';
   &debug('start_data = '.ord($start_data));
   &debug('end_data = '.ord($end_data));
   for(split(//,$display_text)) { $test .= "$_ = ".ord($_).", "; }
   &debug('Einzelzeichen = '.$test);

   $display_text =~ s/$start_data([^$end_data]+?)$end_data/$sheet->Range(&get_a1($nr, &array_index($1, @headlines)))->{Value}/sgei;
   $text_display->delete("0.0", "end");
   $text_display->insert("end", $display_text);
 }

 utf8::downgrade($display_text);

truss perl -e '$x="\x{20ac}"; $x =~ m{\w}' |& grep '^open'
open("/etc/libmap.conf",0x0,0666)                = 3 (0x3)
open("/usr/local/lib/perl5/5.8.8/mach/CORE/libperl.so",0x0,00) = 3 (0x3)
open("/var/run/ld-elf.so.hints",0x0,044)         = 3 (0x3)
open("/lib/libm.so.4",0x0,027757760070)          = 3 (0x3)
open("/lib/libcrypt.so.3",0x0,027757760070)      = 3 (0x3)
open("/lib/libutil.so.5",0x0,027757760070)       = 3 (0x3)
open("/lib/libc.so.6",0x0,027757760070)          = 3 (0x3)
open("/usr/share/locale/de_DE.ISO8859-1/LC_COLLATE",0x0,0666) = 3 (0x3)
open("/usr/share/locale/de_DE.ISO8859-1/LC_CTYPE",0x0,0666) = 3 (0x3)
open("/usr/share/locale/de_DE.ISO8859-1/LC_MONETARY",0x0,05001220541) = 3 (0x3)
open("/usr/share/locale/de_DE.ISO8859-1/LC_NUMERIC",0x0,043) = 3 (0x3)
open("/usr/share/locale/de_DE.ISO8859-1/LC_TIME",0x0,06) = 3 (0x3)
open("/usr/share/locale/de_DE.ISO8859-1/LC_MESSAGES",0x0,0557) = 3 (0x3)
open("/dev/urandom",0x0,05001162001)             = 3 (0x3)
open("/dev/null",0x0,0666)                       = 3 (0x3)
open("/usr/local/lib/perl5/5.8.8/utf8.pm",0x0,0666) = 3 (0x3)
open("/usr/local/lib/perl5/5.8.8/utf8_heavy.pl",0x0,0666) = 3 (0x3)
open("/usr/local/lib/perl5/5.8.8/strict.pm",0x0,0666) = 4 (0x4)
open("/usr/local/lib/perl5/5.8.8/warnings.pm",0x0,0666) = 4 (0x4)
open("/usr/local/lib/perl5/5.8.8/Carp.pm",0x0,0666) = 5 (0x5)
open("/usr/local/lib/perl5/5.8.8/Exporter.pm",0x0,0666) = 5 (0x5)
open("/usr/local/lib/perl5/5.8.8/unicore/PVA.pl",0x0,0666) = 3 (0x3)
open("/usr/local/lib/perl5/5.8.8/unicore/Exact.pl",0x0,0666) = 3 (0x3)
open("/usr/local/lib/perl5/5.8.8/unicore/lib/gc_sc/Word.pl",0x0,0666) = 3 (0x3)