Hello Monks!

I am trying to create a Win32 application (with Strawberry Perl (v5.14.4) on Win10) displaying graphic computations. In order to optimize the process, I want to divide the management of my virtual buffer into small pieces computed by individual threads, then compile the results and copy the virtual buffer on the screen.

My problem is the combination of Win32::GUI and threads (I have also tried forkmanager without success). Threads without Win32 is ok, Win32 without threads is ok, but using both is not. Here is a simple sample code to illustrate the issue (you can enable/disable the use of Win32 with the variable $use_win or change the amount of threads with the variable $t_amount):

#!/bin/perl
use Win32::GUI();
use threads;
use strict;
use warnings;
use Data::Dumper;

my $use_win=1;  # Create Win32 GUI interface (1) or not (0)
my $t_amount=4; # Amount of threads to create

my $textbox;
my $win;
my $draw;

if($use_win){
  # Initialize window
  $win=new Win32::GUI::Window(
      -left   => 0,
      -top    => 0,
      -width  => 300,
      -height => 300,
      -name   => "Window",
      -text   => "Test",
  );
  $win->InvalidateRect(1);
  $textbox=$win->AddTextfield(
    -name   => "Output",
    -left   => 5,
    -top    => 5,
    -width  => 275,
    -height => 255,
    -text => "");
  
  # Start application
  $draw=$win->AddTimer('draw',1000);
  $win->Show();
  Win32::GUI::Dialog();
}else{
  draw_Timer();
}

sub Window_Terminate{-1}

sub draw_Timer{
  my @threads;
  my @ret;
  my $c;
  my $d;

  # Assign range of computation to fork processes
  foreach $c(1..$t_amount){
    $d=$c-1;
    push(@threads,threads->new(\&draw,($d*10),($d*10+10)));
  }
  foreach my $thread(@threads){
    @ret=$thread->join;
    foreach my $data(@ret){
      $use_win?$textbox->Append("|".$data):print"|".$data;
    }
    $use_win?$textbox->Append("\n"):print"\n";
  }
}

sub draw{
  my $begin=shift;
  my $end=shift;
  my @tbl;
  my $cpt;

  for($cpt=$begin;$cpt<$end;$cpt++){
    push(@tbl,$cpt);
  }
  return(@tbl);
}
[download]

Any help would be welcome. I have searched for previous posts without finding a solution. I also googled with no luck. Thanks in advance!