Tkinter Listbox.curselection() error?

[Bob]

Hello,
I'm trying to write a fairly simple font selection dialog for a bigger
application I'm working on.  Every time I try to use the
curselection() method on a listbox I created I get a weird tcl error. 
Can anyone tell me what I'm doing wrong?  Any help would be much
appreciated.

Thanks,
-Bob

Error text:
Traceback (most recent call last):
  File "ERGFontChooser.py", line 104, in ?
    f = fb.getFont();
  File "ERGFontChooser.py", line 71, in getFont
    items = self.familyBox.curselection();
  File "C:\Python22\lib\lib-tk\Tkinter.py", line 2285, in curselection
    return self.tk.splitlist(self.tk.call(
TclError: invalid command name ".9321880.9318744.9334288"

My code:
(sorry for the linewraps, I've been using 4-space tabs)
###########################################################
# ERGFontChooser.py

from Tkinter import *
from tkFont import *

class ERGFontChooser:
	# a simple font selectiondialog

	def __init__( self, root ):
		self.root = root;

		self.top = Toplevel( root );

		self.top.protocol( "WM_DELETE_WINDOW", self.cancel );
		self.top.bind( "<Return>", self.ok );
		self.top.bind( "<Escape>", self.cancel );

		f1 = Frame( self.top );
		Label( f1, text = "Font: " ).grid( row = 0, column = 0 );

		# create the listbox and scroll bar
		scrollbar = Scrollbar( f1, orient=VERTICAL );
		self.familyBox = Listbox( f1, height = 5,
		                          yscrollcommand = scrollbar.set );
		scrollbar.config( command = self.familyBox.yview );
		scrollbar.grid( row = 0, column = 2, pady=5, sticky = W+N+S );
		self.familyBox.grid( row = 0, column = 1, pady = 5 );

		# fill the listbox
		for fam in families():
			self.familyBox.insert( END, fam );

		# create size selection
		Label( f1, text = "Size: " ).grid( row = 1, column = 0 );
		sizeFrame = Frame( f1 );
		dnb = Button( sizeFrame, text = "-", command = self.sizeDown,
		              width = 1, height = 1);
		dnb.grid( row = 0, column = 0 );
		self.sizeVar = StringVar();
		self.sizeVar.set( "10" );
		sen = Entry( sizeFrame, textvariable = self.sizeVar, width = 2 );
		sen.grid( row = 0, column = 1, padx = 5 );
		upb = Button( sizeFrame, text = "+", command = self.sizeUp,
		              width = 1, height = 1);
		upb.grid( row = 0, column = 2, padx = 5 );
		sizeFrame.grid( row = 1, column = 1, padx = 5, pady = 5, sticky = W
);

		# create bold selection
		self.boldVar = IntVar();
		self.boldVar.set( 0 );
		cb = Checkbutton( f1, text = "Bold", variable = self.boldVar );
		cb.grid( row = 2, column = 1, columnspan = 2, sticky = W, pady = 5
);

		f1.pack();

		f2 = Frame( self.top );
		okb = Button( f2, text = "OK", command = self.ok, width = 10 );
		cnb = Button( f2, text = "Cancel", command = self.cancel, width =
10);

		okb.grid( row = 0, column = 0, padx = 5, pady = 5 );
		cnb.grid( row = 0, column = 1, padx = 5, pady = 5 );

		f2.pack();

	def getFont( self ):

		self.top.update_idletasks();
		self.top.lift();
		self.top.grab_set();

		self.root.wait_window( self.top );

		# we have returned
		items = self.familyBox.curselection();
		fam = self.familyBox.get( items[0] );
		if( self.boldVar.get() == 0 ):
			weight = NORMAL;
		else:
			weight = BOLD;

		font = Font( self.root, family = fam );
		font.config( size = self.sizeVar.get(), weight = weight );

		return font;

	def sizeUp( self, event = None ):
		size = int( self.sizeVar.get() ) + 1;
		self.sizeVar.set( `size` );
	
	def sizeDown( self, event = None ):
		size = int( self.sizeVar.get() ) - 1;
		self.sizeVar.set( `size` );

	def ok( self, event=None ):
		print "OK";
		self.top.destroy();

	def cancel( self, event = None ):
		print "Cancel";
		self.top.destroy();


if( __name__ == "__main__" ):
	root = Tk();
	fb = ERGFontChooser( root );

	f = fb.getFont();

	print( `f` );
	print( f.actual() );