finaly found a souloution that works its a bit different from my first approch but it works (in fact the solution is to use a socket and to "poll" the socket yourself ....) something like this :

#!/urs/bin/perl -w

use strict;
use warnings;
use IO::Socket;
use Tk;
use subs qw/read_sock/;

my $mw;
my $sel;
my $sock;
my $text;
my $line;
my $scriptname = "my_script.pl";

#some Tk 
$mw = MainWindow->new();
$text = $mw->Text->pack;
my $goButton = 
    $mw->Button(
        -text=> "Accept",
        -command => \&go

    )->pack(
        -side=>"left",
    );

#"polling" socket
$mw->repeat(50 => \&read_sock);

MainLoop;


sub read_sock{
    return unless $sock;
    my $hand = $sock;
    my @ready = $sel->can_read(0);
    return if $#ready == -1;
    $hand = $ready[0];
    my $numbytes = 1;
    my $buf;
    sysread $hand, $buf, $numbytes;
    print "read a $buf\n";
    $line .= $buf;
    if ($buf eq "\n"){
        if ($line eq "EOF\n"){
            undef $sel;
            undef $sock;
            undef $line;
            return;
        }
        $text->insert('end',"$line");
        undef $line;
    }
}

sub go{
    my $ProcessObj;    
    require Win32;
    require Win32::Process;
    Win32::Process::Create($ProcessObj,
        "c:\\perl\\bin\\perl.exe",
        "perl $scriptname",
        0,
        0,
        ".")|| die ErrorReport();
    sleep 2; # let the script time to built the socket
    $sock = IO::Socket::INET->new(PeerAddr=> 'localhost:13579');
    die "cannot connect: $!\n" unless defined $sock;
    use IO::Select;
    $sel = IO::Select->new();
    $sel->add($sock);
}
[download]

and in $scriptname

#!/usr/bin/perl -w

use IO::Socket;
use strict;

my $socket = IO::Socket::INET->new(
    Listen        => 5,
    Reuse        => 1,
    LocalPort    => 13579,
    Proto        => 'tcp',
)||die "couldn't open socket : $!\n";

my $new_socket = $socket -> accept();

#so far so good

#if the is $something_to_say  
syswrite $new_socket, "$something_to_say\n";
[download]

and to sigal the end to the parent (since there is no sigchld when using Win32::Process)

END{
    syswrite $new_socket, "EOF\n";
}
[download]

----
NaSe
:x