4.2. The Origins of XUL Widgets

The NPA diagram gives an overview of the technologies used inside Mozilla as a whole. The boxes in that diagram can be rearranged to show the anatomy of a single XUL widget. XUL contains a wide variety of tags, and not all of them are constructed along the same lines. Figure 4.3 is a useful guide that applies in most cases.

Figure 4.3. Widget construction stack.

At the bottom of the stack are the resources provided by an operating system like Windows, MacOS, or UNIX. At the top of the stack is a user control in a finished application. In between, the low-level services of the operating system are gradually abstracted ...

Get Rapid Application Development with Mozilla™ now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.