Julian Smart, "Cross-Platform GUI Programming with wxWidgets" (repost)

This book is a guide to using wxWidgets: an open-source construction kit to help you write sophisticated C++ applications for a variety of platforms, including Windows, Linux, Mac OS X, and Pocket PC. With help from this book, a competent programmer can create multi-platform applications with confidence. Developers already familiar with wxWidgets should also find it useful for brushing up their knowledge.
This book is accessible to developers with a variety of experience and backgrounds.