Would you like to learn how to make rich user interfaces with nothing more complicated than a text editor? Welcome to XUL, a subset of XML used to describe user interfaces. This article will get you started.
Many of you may not have heard of XUL. [I] hadn’t until recently. If you’re excited by the prospect of making rich user interfaces, quickly and easily, using nothing but a simple text editor, then you’ll want to learn all about XUL, because that’s exactly what it’s for. It’s pronounced to rhyme with "cool" and is a W3C compliant subset of XML that is used specifically to describe user interfaces. It stands for XML User interface Language, and was designed to implement the user interface of the Mozilla suite (including the browser and the Thunderbird email client.)
If you have even just the browser part of the Mozilla interface installed (or Netscape Navigator, or Firefox), do a quick search for *.xul and see how many files are matched. Okay, so there aren’t hundreds, but there are a few, right? These files (and others tucked away in jar files) are used to present the interface through which you use Mozilla. The side bar, for example is a XUL file that is loaded when the application is launched. Netscape Navigator and Firefox also make extensive use of XUL, and you can too.
Interestingly enough, Netscape Navigator has some built in XUL examples that you can play around with to see at a basic level how XUL works.