Myk Melez gave this tutorial presentation on developing extensions as part of the Mozilla Labs Design Challenge. It provides a quick introduction to the concept of extensions and proceeds to give you the basics on how to develop an extension.
Among the topics covered:
- What are extensions, what can they do, and what are they made of?
- How do you configure your development environment on Windows, Mac OS X, or Linux?
- How do you construct an extension? What files and directories are needed?
- How do you package and test your extension?
- A simple extension is then built that inserts XUL into the main browser window using an overlay, styles it with CSS, listens for and handles a DOM event using JavaScript, and localizes its strings with both a DTD and a properties file.
Download the presentation slides.