#!/usr/bin/perl -w
use strict;
use Gtk2 '-init';
use Glib qw/TRUE FALSE/;

#shared variables
my $active_interface: shared;

#create dummy main window
my $main_window = Gtk2::Window->new('toplevel');
$main_window->signal_connect(delete_event=> sub{Gtk2->main_quit});

my $label = Gtk2::Label->new('TEST      ');

my $main_table = Gtk2::Table->new(2, 1, FALSE);

$main_table->attach_defaults($label, 0, 1, 0, 1);

$main_window->add($main_table);

$main_window->show_all;

&start_up;

Gtk2->main;

#The start up askng the user what position they are in
sub start_up{
  #the User interface select window
  my $start_up = Gtk2::Window->new('toplevel');

  #create table
  my $job_table = Gtk2::Table->new(3, 1, FALSE);

  #label
  my $job_label = Gtk2::Label->new("      Select User Interface       
+");

  #Combobox to select user
  my $job_select = Gtk2::ComboBox->new_text;
  $job_select->append_text('Spotter');
  $job_select->append_text('Tracker');
  $job_select->append_text('VC Base');
  $job_select->append_text('Met Base');
  $job_select->set_active(0);

  #add the Ok button
  my $job_button = Gtk2::Button->new('Start');

  #add to table
  $job_table->attach_defaults( $job_label, 0, 1, 0, 1);
  $job_table->attach_defaults( $job_select, 0, 1, 1, 2);
  $job_table->attach_defaults( $job_button, 0, 1, 2, 3);

  #add widgets
  $start_up->add($job_table);

  $start_up->show_all;
  
  #capture the interface type to use and display in the main window
  $job_button->signal_connect('button-press-event' => sub { $active_in
+terface = $job_select->get_active_text; my $active_interface_label = 
+Gtk2::Label($active_interface); $main_table->attach_defaults($active_
+interface_label, 0, 1, 1, 2); $start_up->destroy});
  
}
[download]

I think your problem is that when you create the Label in the callback you do Gtk2::Label($active_interface); and that should be Gtk2::Label->new($active_interface); (of course, you still need to show_all on the main window)

HTH, --traveler