#!/usr/bin/perl -w
use Tk;
use Tk::ExecuteCommand;
use Tk::widgets qw/LabEntry/;
use strict;

my $mw = MainWindow->new;

my $ec = $mw->ExecuteCommand(
    -command    => '',
    -entryWidth => 50,
    -height     => 10,
    -label      => '',
    -text       => 'Execute',
				  )->pack;
$ec->configure(-command => 'date; sleep 10; date');


my $button = $mw->Button(-text =>'Do_it',
                         -background =>'hotpink',
                         -command => sub{ $ec->execute_command },
                        )->pack;
 
MainLoop;

##</code><code>##

#!/usr/bin/perl
use warnings;
use strict;
use threads;
use threads::shared;

# declare, share then assign

my $data_in:shared = 0;
my $data_ret:shared = '----';
my $button_control:shared = 0;
my $go_control:shared = 0;
my $die_control:shared = 0;

#create thread before any tk code is called
my $thr = threads->create( \&worker );

use Tk;
my $mw = MainWindow->new();
my $val = '----';

    my $label = $mw->Label(
         -width => 50,
         -textvariable => \$val )->pack();
 
    my $button = $mw->Button( -text => 'Start',
                              -command => \&start )->pack();
 
# you need a timer to read the shared var in thread
   my $timer = $mw->repeat(10 , sub{
                  $val = $data_ret;
                });

   my $timer1 = $mw->repeat(10, sub{  if($button_control){
                                         $button ->configure(-text=> "Next");
                                         $button_control = 0;
                                         }            
                                   });
                                     
MainLoop;

sub start{
  $button ->configure(-text=> "----");
  $go_control = 1;
  $data_in = int rand(20);  # pass some new data in
}


# no Tk code in thread
sub worker {
   my $count;
    while(1){
      
      if($die_control){
             print "thread finishing\n"; 
             return} 
      
      #wait for $go_control  
      if($go_control){      
          
                 if($die_control){
                    print "thread finishing\n"; 
                           return} 
               
               print "incoming $data_in\n";
               
               $count++;            
               print $count,"\n";
	       if($count >= $data_in){ $go_control = 0; $data_ret = $count; $button_control = 1;}
	       $data_ret = $count;
	       select(undef,undef,undef,.25);
	     
	  
        }else{ 
         $count = 0;
         select(undef,undef,undef,.25); }# sleep until awakened 
   }
	
  return;
}