WordPress at a glance
action is not described

the_widget action-hook . WP 3.0.0

Fires before rendering the requested widget.

Usage

add_action( 'the_widget', 'action_function_name_2448', 10, 3 );
function action_function_name_2448( $widget, $instance, $args ){
	// action...
}
$widget(string)
The widget's class name.
$instance(array)
The current widget instance's settings.
$args(array)
An array of the widget's sidebar arguments.

Where the hook is called

the_widget()
wp-includes/widgets.php 1095
do_action( 'the_widget', $widget, $instance, $args );

Where the hook is used (in WP core)

Does not used.