diff --git a/addons/web/static/src/js/framework/session.js b/addons/web/static/src/js/framework/session.js
index b114cbef7b7..3ae6ddb6649 100644
--- a/addons/web/static/src/js/framework/session.js
+++ b/addons/web/static/src/js/framework/session.js
@@ -418,3 +418,50 @@ var Session = core.Class.extend(mixins.EventDispatcherMixin, {
 return Session;
 
 });
+
+
+odoo.define('web.config', function (require) {
+"use strict";
+
+var bus = require('web.core').bus;
+// Configuration module.
+// To do: refactor session, and this module in a sane way.  Session accomplish
+// several concerns (rpc, configuration, currencies (wtf?), user permissions, ...)
+// they should be clarified and separated.
+
+var medias = [
+    window.matchMedia('(max-width: 767px)'),
+    window.matchMedia('(min-width: 768px) and (max-width: 991px)'),
+    window.matchMedia('(min-width: 992px) and (max-width: 1199px)'),
+    window.matchMedia('(min-width: 1200px)')
+];
+_.each(medias, function(m) {
+    m.addListener(set_size_class);
+});
+
+var config = {
+    debug: ($.deparam($.param.querystring()).debug !== undefined),
+    device: {
+        touch: 'ontouchstart' in window || 'onmsgesturechange' in window,
+        size_class: size_class(),
+        SIZES: { XS: 0, SM: 1, MD: 2, LG: 3 },
+    },
+};
+
+function size_class() {
+    for(var i = 0 ; i < medias.length ; i++) {
+        if(medias[i].matches) {
+            return i;
+        }
+    }
+}
+function set_size_class() {
+    var sc = size_class();
+    if (sc !== config.device.size_class) {
+        config.device.size_class = sc;
+        bus.trigger('size_class', sc);
+    }
+}
+
+return config;
+});