benjaminjackson

Looks like the WP team left that function out of widgets.php in the version I downloaded as well. Add this code at the top widgets.php, it worked for me:

function wp_widget_description( $id ) {
  if ( !is_scalar($id) )
    return; 

  global $wp_registered_widgets; 

  if ( isset($wp_registered_widgets[$id]['description']) )
    return wp_specialchars( $wp_registered_widgets[$id]['description'] );
}