+$_wp_editor_expand = $_content_editor_dfw = false;
+
+/**
+ * Filter whether to enable the 'expand' functionality in the post editor.
+ *
+ * @since 4.0.0
+ * @since 4.1.0 Added the `$post_type` parameter.
+ *
+ * @param bool $expand Whether to enable the 'expand' functionality. Default true.
+ * @param string $post_type Post type.
+ */
+if ( post_type_supports( $post_type, 'editor' ) && ! wp_is_mobile() &&
+ ! ( $is_IE && preg_match( '/MSIE [5678]/', $_SERVER['HTTP_USER_AGENT'] ) ) &&
+ apply_filters( 'wp_editor_expand', true, $post_type ) ) {
+
+ wp_enqueue_script('editor-expand');
+ $_content_editor_dfw = true;
+ $_wp_editor_expand = ( get_user_setting( 'editor_expand', 'on' ) === 'on' );
+}