WordPress at a glance
action is not described

widgets.php action-hook . WP 2.8.0

Fires early when editing the widgets displayed in sidebars.

Usage

add_action( 'widgets.php', 'action_function_name_9372' );
function action_function_name_9372(){
	// action...
}

Where the hook is called

wp_ajax_save_widget()
WP_Customize_Widgets::customize_controls_init()
WP_Customize_Widgets::wp_ajax_update_widget()
wp_ajax_delete_inactive_widgets()
wp-admin/includes/ajax-actions.php 1936
do_action( 'widgets.php' );
wp-admin/includes/ajax-actions.php 2030
do_action( 'widgets.php' );

Where the hook is used (in WP core)

Does not used.