I found this book quick and easy to read and a good introduction whilst also going into sufficent detail.

Importantly for me it contains information on how to go about creating a remote application to run over the Internet and using serverside PHP, neither of which have I seen mentioned elsewhere.

The book is not perfect but it is useful and I think some of the other reviewers have been unduly harsh; I am glad that I was not put off.

Clearly, the authors did not sit down and make a coherent plan of what the best way to introduce each topic to the neophyte. This stands in stark contrast to the various O'Reilly Perl books that always seem to give the overview in clear terms and then flesh it out, instead of diving into the middle and trying to explain it as you go.

The only reason right now to get this book is because it appears to be the only (or one of the only) ones on the topic at this time. Hopefully _Rapid Application Development with Mozilla_ due out in November this year will get it right.

Chapters 1-6 lead the reader through the progressive steps required to build and package a Mozilla-based application. The authors create a demo application called xFly which is used as a test bed to show the different features of XUL, CSS, and JavaScript. By the end of Chapter 6, this application contains a tree control, a bunch of sample menus, and various other assorted UI widgets. But it doesn't really _do_ anything. Maybe I'm too picky, but I'd rather see an application that has some function, even if all it does is play tick-tack-toe. Then, to me at lease, it's much clearer how the different pieces would fit together in a "real-world" application.

Chapters 7-12 cover more exotic and difficult aspects of Mozilla
programming such as the Extensible Binding Language (XBL), XPCOM (Mozilla's component object model), and accessing web services from XUL applications. These chapters are very dense in technical details, with good references to online resources for further study. Overall, I found this book to be a very succinct source of accurate information about building applications with Mozilla. Its only weakness seems to be that it focuses too much on low-level implementation details without giving the reader (who may be new to the idea of XML-based GUI
application programming entirely) a good high-level overview of the benefits of this type of development and which technologies serve which purpose. Chapter 1 is the only chapter that explicitly addresses high-level application architecture, and it is only 8 pages long.

The bottom line is that this is a good reference book for people who already know how and why to build applications based on Mozilla, but a not-so-good introduction and tutorial for people who are completely new to the XUL-CSS-JavaScript paradigm of application development.

I am puzzled that other reviewers claim XUL and Mozilla are not ready for mainstream since the fact that an entire browser, mail, chat, editor, JS debugger and hundreds more third party extensions and apps have been written using it demonstrates it is. It certainly needs tools and add robustness, but it is already a viable and strong technology for producing platform neutral applications.

It is well worth the money, however it should be revised to reflect the latest Mozilla developments. As an added bonus, the source for this book is actually online so you can evaluate it yourself at books.mozdev.org before buying it.