This is a segment of a much larger code line. This code segment controls the GPS device. The user clicks the "Start" button to start the device and clicks "Stop" to stop the device. The problem I am having with is when the GPS device is not responding and the user tries to close the program. When the user clicks "Start" then "Stop" and tries to close the program, the program hangs and stops responding. I can't seem to see the problem in the code and some new eyes may help. 
#!/usr/bin/perl -w
use strict;
use Gtk2 '-init';
use Glib qw/TRUE FALSE/;
use GPS::NMEA;
use threads;
use threads::shared;

my $notebook;
my $gps_entry;
my $gps_start:shared = 0;
my $die:shared = 0;
my($ns,$lat,$ew,$lon):shared;
my $gps_current;

######################################################################
+#############################
#start threads
my $thread_gps = threads->new( \&gps);

######################################################################
+#############################
#timeouts
my $timer_gps = Glib::Timeout->add(100, \&gps_position);

######################################################################
+#############################

#create window
my $window = Gtk2::Window->new('toplevel');
$window->signal_connect(delete_event=> sub {$die = 1; $thread_gps->joi
+n; Gtk2->main_quit});
$window->set_title("GPS Test");
  
#create notebook
$notebook = Gtk2::Notebook->new;
$notebook->set_tab_pos('top');

my $gps_table = Gtk2::Table->new(3, 2, FALSE);

#GPS Group (for all users)
my $gps_instruction = Gtk2::Label->new();
$gps_instruction->set_markup( '<span size="small">Enter the location o
+f the GPS device (i.e. "COM4" or "/dev/lao")</span>');
my $gps_label = Gtk2::Label->new( 'Location');
$gps_current = Gtk2::Label->new;
$gps_entry = Gtk2::Entry->new();
$gps_entry->set_text("COM4");
my $start_stop = Gtk2::Button->new("Start");
$gps_table->attach_defaults($gps_instruction, 0, 2, 0, 1);
$gps_table->attach_defaults($gps_label, 0, 1, 1, 2);
$gps_table->attach_defaults($gps_entry, 1, 2, 1, 2);
$gps_table->attach_defaults($start_stop, 0, 1, 2, 3);
$gps_table->attach_defaults($gps_current, 1, 2, 2, 3);
#start and stop GPS device
$start_stop->signal_connect('clicked' => sub {if ( $start_stop->get_la
+bel eq "Start") {$start_stop->set_label("Stop"); $gps_start = 1;  pri
+nt "$gps_start\n";} else {$start_stop->set_label("Start"); $gps_start
+ = 0; print "$gps_start\n";}});

$notebook->append_page($gps_table, "GPS");

#add widgets
$window->add($notebook);
 
$window->show_all;
  
Gtk2->main;

######################################################################
+##############################
#GPS Thread
sub gps{
  while (1) {
    #If program ends stop the loop
    goto END if $die == 1;
    
    if ($gps_start == 1) {
      
      #start the GPS Device
      my $gps_device = GPS::NMEA->new(Port => 'COM4', Baud => 4800);
      
      print "$gps_device\n";
      
      #start the loop  
      for (;;) {
        #stops the warnings in the GPS device module
        local $^W = 0;
        
        ($ns,$lat,$ew,$lon) = $gps_device->get_position;
        print "$gps_device\n";
        goto END if $die == 1;
        last if $gps_start == 0;
        sleep 3;
      }
      print "$gps_device\n";
      #undef $gps_device;
    } else {sleep 4}
  }
  END:
}

######################################################################
+##############################

#GPS position timeout
sub gps_position{
  #set the current GPS position
  $gps_current->set_label("$ns $lat, $ew $lon") if $gps_start == 1 and
+ defined($ns);
  $gps_current->set_label("N/A") if $gps_start == 0;
  return 1;
}

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In reply to GPS Widget by deadpickle

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