WP_Widget
Class: Core base class extended to register widgets.
Source: wp-includes/class-wp-widget.php:21
WP_Widget::update_callback()
Method: Handles changed settings (Do NOT override).
Source: wp-includes/class-wp-widget.php:411
WP_Widget::widget()
Method: Echoes the widget content.
Source: wp-includes/class-wp-widget.php:113
widget_update_callback
Filter Hook: Filters a widget’s settings before saving.
Source: wp-includes/class-wp-widget.php:476