learning gtk+ well: Which book to buy?

[Christopher Howard <christopher howard frigidcode com>]

Hi. I want to have a thorough and well-formed understanding of how to
use gtk+, which I'm not quite getting from the API. What would be the
best book I can buy right now? The most up-to-date book I see is
Foundations of GTK+ Development (2007) but not having a lot of money to
experiment with, I was hoping to get your recommendations before buying
anything.

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