Learning Perl/Tk is a good book to learn the basics of how to write code about gui objects in isolation. For example, the book will show you how to draw and interact with a scrollbar on a window.

This book unfortunately does not show you how to write gui applications. There is very little discussion on how to deal with events that trigger activities on multiple gui objects, no discussion on how to deal with the communication between multiple windows, and very little in dealing with composite objects like combo boxes, directory lists, and etc.

If you do not know Perl/Tk this is good book to learn the concepts. You will not be able to write gui applications.

If Nancy Walsh could write another book called Advanced Perl/Tk. Showing how events can trigger multiple activities on different objects, how supplied composite objects work, give more examples of creating composite objects, how Multiple windows would work, and show examples of complete gui applications.
This would fill the void on how to create Perl/Tk applications.