use Tk;
use strict;
require Tk::ProgressBar;
require Tk::Button;

my (
    $mw,
	$progressBar,
	$cancelCalButton,
	$runCalButton,
   );

my $guiPid = $$;

$mw = MainWindow->new();
$cancelCalButton = $mw->Button(-text=>"cancel")->pack();
$runCalButton = $mw->Button(-text=>"run",-command=>\&doit)->pack();
$progressBar = $mw->ProgressBar()->pack();

$SIG{USR1} = sub {
  $progressBar->value(0);
  $mw->update();
  $runCalButton->configure(-state=>"normal");
  $cancelCalButton->configure(-state=>"disabled");
};

MainLoop;

sub doit {
  my $calPid;
            
  $runCalButton->configure(-state=>"disabled");
  $cancelCalButton->configure(-state=>"normal");
  $mw->update;

  print "Failed to fork" if (!defined($calPid = fork()));
  return if ($calPid);
  
  for (1 .. 6) {
    $progressBar->value($_);
    $mw->update();
    sleep(1)
  }

  # send the signal to main GUI to reconfigure the button states
  kill('USR1',$guiPid);
  kill('INT',$$);
}


##</code><code>##

X Error of failed request:  BadIDChoice (invalid resource ID chosen for this connection)
  Major opcode of failed request:  53 (X_CreatePixmap)
  Resource id in failed request:  0x1e00077
  Serial number of failed request:  1374
  Current serial number in output stream:  1300