Title: Mastering Perl/Tk

 Subtitle: Graphical User Interfaces in Perl
 Authors: [Nancy Walsh]
        [Stephen Lidie]
 Publisher: [O'Reilly]
 Publication date: 2002
 ISBN: 1565927168
 Pages: 766
 Price: 44.95 US
 WWW book information:  http://www.oreilly.com/catalog/mastperltk/
 Book's examples:  http://examples.oreilly.com/mastperltk/
 Errata:  http://www.oreilly.com/catalog/mastperltk/errata/

This book, nominally on Perl/Tk, is good enough and deep enough that I've heard even Tkinter practitioners mention it as a help! UnixReview ran a review [1] of it not long after it first appeared. Notice that [Stephen Lidie]'s [BOOK: Perl/Tk Pocket Reference] also remains in print.