Ticket #16773: 16773.2.diff

wp-includes/class-wp-widget.php

@@ -152 +152 @@
          *                                information on accepted arguments. Default empty array.
          */
         public function __construct( $id_base, $name, $widget_options = array(), $control_options = array() ) {
-                $this->id_base = empty($id_base) ? preg_replace( '/(wp_)?widget_/', '', strtolower(get_class($this)) ) : strtolower($id_base);
+                $this->id_base = empty($id_base) ? preg_replace( '/(wp_)?widget_/', '', sanitize_key( get_class( $this ) ) ) : sanitize_key( $id_base );
                 $this->name = $name;
                 $this->option_name = 'widget_' . $this->id_base;
                 $this->widget_options = wp_parse_args( $widget_options, array('classname' => $this->option_name) );