... are comfortable with how JavaScript works in the context of the user interface layer and are familiar with some of the primary DOM methods used to manipulate the various elements and attributes, ... to start and stop. When the user clicks a XUL button, for instance, the button "listens" for the click event, and may also handle that event. If the button itself does not handle the ... in the first example, the button getting clicked in the second, and so on) was fired and handled. As in HTML, predefined event handlers are available as attributes on a XUL element. These attributes...