use
Syntax:
use="a-class-name"
use="${EL_returns_a_class_or_a_class_name}"
use="${a_component}"
It specifies a class to create a component instead of the default one.
In the following example, MyWindow is used instead of the default
class,
<window use="MyWindow"/>
If an EL expression is used, it can return a class name, a class instance, or a component instance. Notice that, if the expression returns a component, the component should not belong to any pages.