Thank you so much. I always think one should post the working solution once found so I have posted the working script below. I am running Xubuntu 12.04 - a Linux system

AnonyMonk's post at first seemed too minimalistic but it actually led me finally to the solution. Here is a working script that runs from the command line and opens a listbox that is contained in a subroutine, allows one to select an item and closes the listbox when selection is done with a double click returning the id of the selected item to the command line program where further actions can use the information.

#!/usr/bin/perl
use strict;
use Tk;

my @listbox_items = qw/frodo bilbo rabbits orcs smaug gandolf/;
my $choice = &myListBox(@listbox_items);
print "TOP: selection is $choice\n";

sub myListBox{
my $choice;
my @listbox_items = @_;
my $mw = MainWindow->new;
   $mw->geometry('400x300');
   $mw->Label(-text => "Click once to select item")->pack();
   $mw->Label(-text => "Double-click selects item and closes window")-
+>pack();
       my $lb = $mw->Listbox(-selectmode => "single",
                            -exportselection =>1,)->pack( );
       $lb->insert('end', @listbox_items);
       $lb -> bind('<Button-1>'=> sub {
                    $choice = $_[0]->get($_[0]->curselection),
                     print "in loop selection is $choice\n";},
         );
       $lb -> bind('<Double-Button-1>'=> sub {$mw->destroy();}
       );
MainLoop;
return $choice;
}#endsub
[download]

One of my errors with the intitial script was not being aware of how to distinguish between single click and double click. (sigh).

I am also very grateful to those who created the thread: Tk event bindings - single vs. double click at: