I'm trying to learn Tk and SpecTcl. 

I created this layout with the SpecTcl tool and then hand modified the
commands in it.

Everything works 'visually'. But, I can't seem to figure out the index
value returned from the list box.

Can anyone point me in the right direction?
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#!/usr/bin/env ruby
# Sample SpecTcl main program for testing GUI
require 'tk'
top = TkRoot.new { title "list_scrl_entry1 test" }
# Interface generated by SpecTcl (Ruby enabled) version 1.1
# File: list_scrl_entry1.ui
# For use with Tk8.1 or later, using the grid geometry manager.
def list_scrl_entry1_ui (root) 
	@zzentry = TkVariable.new
	@zzentry.value = "Opening Text"
	hobbies = %w[ Flying Table-Tennis History Reading Writing Programming
Photography
              TV Movies Concerts Theater Opera Ballet ]
	# Widget creation.
	listbox_1 = TkListbox.new(root,
		'height' => '6',
		'width' => '0',
		'selectmode' => 'single',
		'exportselection' => 0
	)
	scrollbar_1 = TkScrollbar.new(root
	)
	entry_1 = TkEntry.new(root,
		'textvariable' => @zzentry,
		'borderwidth' => '4',
		'state' => 'disabled'
	)
	# widget commands
	listbox_1.insert("end", *hobbies)
	listbox_1.yscrollcommand {|y0,yn| scrollbar_1.set(y0,yn)}
		# proc { |first,last| scrollbar_1.set first,last }
		# %B.scrollbar#1 set
	scrollbar_1.configure(
    	'command' =>  proc { |*args| listbox_1.yview(*args) } 
		#%B.listbox_1 yview
	)
	# Geometry management
	listbox_1.grid('in' => root,'column' => 1,'row' => 1,'sticky' =>
'nesw')
	scrollbar_1.grid('in' => root,'column' => 2,'row' => 1,'sticky' =>
'ns')
	entry_1.grid('in' => root,'column' => 1,'row' => 2,	'sticky' =>
'nesw')
	# Container root (rows).
	TkGrid.rowconfigure(root, 1, 'weight'  => 0, 'minsize'  => 26)
	TkGrid.rowconfigure(root, 2, 'weight'  => 0, 'minsize'  => 30)
	# Container root (columns).
	TkGrid.columnconfigure(root, 1, 'weight' => 0, 'minsize' => 268)
	TkGrid.columnconfigure(root, 2, 'weight' => 0, 'minsize' => 14)
	# Additional interface code.
	print "listbox_1 selection " , listbox_1.curselection, "xx \n"
	print "listbox_1 selection " , listbox_1.curselection[0], "xx \n"
	print "listbox_1 selection class " , listbox_1.curselection.class,
"\n"
	listbox_1.curselection.each { |x|   puts x }
	# End additional interface code.
end # list_scrl_entry1_ui
list_scrl_entry1_ui top
Tk.mainloop