Appendix B. Development Tools

This book describes how to create applications using Mozilla. Generally, all parts that go into an application (including XUL, CSS, XBL, and DTD files) need to be built by hand since no complete ready-made development tools or development applications are available that would make these manual processes easier.

Creating all these files by hand is a great way to familiarize yourself with the way Mozilla works, and becoming more familiar with the inner workings of a Mozilla application certainly helps you see how the various parts fit together. Once you are comfortable creating these files by hand, using the platform becomes much easier and Mozilla fulfills its promise as a rich application development framework.

Development tools are important, though, and platforms like Mozilla can't obtain the sort of developer base they deserve until tools that make application creation easier are available. Although some people want to learn everything there is to know about creating applications with Mozilla, many simply want to create something without a lot of fuss.

Mozilla does not yet have a full set of development tools, but currently several development projects help with part of the application creation process. These tools don't make up a full-featured development environment, but they are useful. They also point the way to an area in Mozilla development that has a bright future and is worth watching.

This appendix describes some of the new tools -- including XULKit, Patch Maker, the DOM Inspector, the JavaScript Debugger, and MozillaTranslator -- that are already becoming a part of the regular repertoire of Mozilla developers. By learning about how to use these tools for your own project, you can radically simplify the application development process, especially when you combine these tools.

B.1. XULKit

Much of the manual editing described in Chapters Chapter 6, Chapter 7, and Chapter 8 can be automated with special scripts and templates being developed in the Mozilla source tree's tools/wizards section (these files are referred to collectively as the XULKit and can be found at

These tools help you develop your Mozilla application by generating as much of the basic content, structure, and packaging of an application as possible, leaving you free to work only on the aspects of your application that you care about. We mention XULKit first because it can make setting up new Mozilla applications a snap.

XULKit is essentially a set of two scripts:, which creates a new application framework, and, which packages your application once you finish developing it.

B.1.1. Script

Though it's not named very elegantly, the Perl script takes information you provide in the form of a simple text file and uses it to create various parts of a Mozilla application. These parts include the XUL content, which has a basic menubar you can add to; an overlay that puts an item for your application into the Tools menu in the Mozilla browser; CSS for your XUL; and an installation script for the application package. You can base your application off of a couple of different templates, including a sophisticated one that lets you generate XPCOM interfaces for components you wish to use in your application, described below.

Using these scripts, you can add content and logic to your application, restyle it, or build your application however you would like. You can also register the resulting directory with the chrome registry to see it working in your local copy of Mozilla, and when you finish developing it, the application directory is already structured in exactly the way it must be to be checked into the Mozilla source tree's extensions directory (if you want to check it into this common location for applications that become a part of Mozilla). When you want to distribute your application as described in Chapter 6, you can use the other script in the XULKit,, to package your application files into a cross-platform archive that can be installed from a regular web page.

To use the script, point it at a template that you filled out with your own information. It then generates the basic application code in the appropriate subdirectory structure:      -t FILE [-o DIRECTORY] [-f[d]] [-h] [-?]

When you run the script, the XULKit creates a new top-level application directory. In this directory, the script creates the three main package directories, and it places some basic content in each one: a CSS file called mozreg.css in the skins subdirectory, a few XUL files in the content directory (including the overlay that defines a new menu item for the main browser that opens this new application), and localizable data in the mozref.dtd file in the locale subdirectory.

In addition to these files, the XULKit script creates contents.rdf files that describe each package, some Makefiles that instruct the Mozilla build process how to integrate this application into the build (which is a later step and not necessary to run the application), and an install.js file that executes the installation of this application when it appears in a XPI. (See Chapter 6 for more information about XPI, Mozilla's cross-platform installation file format.)

If you look at Example B-1 -- xul-app.tpl, which comes with the distribution of -- you can see how easy it is to fill out the basic information and create your own template.

You can adapt the xul-app.tpl for your own purposes or use the sample.xul-app.tpl that is already filled out. Table B-1 details different options for

B.1.2. Script

In addition to the template-generating script described above, a second script takes your working application and creates an installable package, or XPI, out of it. This way, you can distribute it to others in the same way the various components of the Mozilla browser are distributed and installed when you use the Mozilla installer.

This script,, takes an application directory as input and generates an XPI archive. It also manifests for various parts of your application, the installation script that goes inside this archive, and even the installation web page itself. While is designed to help you start your application, takes your locally developed application and makes it into a package that can be distributed to other users and installed via the Web.

To use, point it at a configuration file that you have edited to point at your application directory:      [-c <config-file>] [-d] [-r <revision>] [-?]

For example, to create a XPI out of your MyApp application directory, in which you created a file called MyApp.conf that defines the variables needs, execute the script as follows:

perl -c ~/appdev/MyApp/makexpi.conf -r 0.9.9

A makexpi.conf file defines the variables needs to know about. Example B-3 shows an example of this file.

Table B-2 lists the options that are recognized by

When you run the script against the configuration file, you end up with two separate pieces -- the XPI in which your application and its installation script are stored and a web page that you can post on a server to guide the XPI's installation. As described in Chapter 6, the web page interacts with the XPI's install.js to install and register your application in Mozilla. If you start your application with the script, then a template-processed version of install.js that works with your application is included as templates/xpi/install.js as part of the XULKit package.