add preferences bug as known issue

web_widget_image_download/README.rst

@@ -26,6 +26,7 @@ Known Issues / Roadmap
 ======================
 
 * In order to work correctly, this widget has to detect image type, the server should include this information in the `Content-Type` header. Right now, odoo is not doing so, but a fix has been `proposed <https://github.com/odoo/odoo/pull/12918>`_.
+* For some unknown reason, the widget does not work in the `Preferences` view, because odoo is not rendering the **QWeb** template.
 
 Bug Tracker
 ===========

web_widget_image_download/__init__.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 Flavio Corpa <flavio.corpa@tecnativa.com>
+# License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl).

web_widget_image_download/static/src/js/web_widget_image_download.js

@@ -16,7 +16,7 @@ openerp.web_widget_image_download = function (instance) {
             $.ajax({
                 type: 'HEAD',
                 url: this.imgSrc,
-                complete(xhr) {
+                complete: function (xhr) {
                     // retrieve image type from server ("Content-Type" header)
                     $widget.attr('download', xhr.getResponseHeader("Content-Type").replace('/', '.'));
                 }