// Register a custom BuddyPress widget
function register_buddypress_custom_widget() {
    register_widget('BuddyPress_Custom_Widget');
}
class BuddyPress_Custom_Widget extends WP_Widget {
    function __construct() {
        parent::__construct('bp_custom_widget', 'BuddyPress Custom Widget');
    }
    function widget($args, $instance) {
        echo '<div class="bp-custom-widget">';
        echo '<p>Custom widget content</p>';
        echo '</div>';
    }
}
add_action('widgets_init', 'register_buddypress_custom_widget');