XML views use event handlers as attributes: The attribute name is the event name, such
as "press" for a button, and the attribute value is the event handler name.
Applying preprocessing to views enables you to use features like XML templating. This
feature is currently only enabled for XML views. On an abstract level, preprocessing means
that a view can be modified during runtime before it is rendered. This makes it possible to
use the templating syntax, as it is interpreted by the preprocessor. It also makes it
possible to apply user customization.