Add desktop notifications, overridable in the same way as other components (although it's not a react component). Also extend the flux dispatcher a little to be less dumb about dispatching while something else is already dispatching.

src/controllers/atoms/EnableNotificationsButton.js

@@ -0,0 +1,64 @@
+/*
+Copyright 2015 OpenMarket Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+'use strict';
+
+module.exports = {
+    notificationsAvailable: function() {
+        return !!global.Notification;
+    },
+
+    havePermission: function() {
+        return global.Notification.permission == 'granted';
+    },
+
+    enabled: function() {
+        if (!this.havePermission()) return false;
+
+        if (!global.localStorage) return true;
+
+        var enabled = global.localStorage.getItem('notifications_enabled');
+        if (enabled === null) return true;
+        return enabled === 'true';
+    },
+
+    disable: function() {
+        if (!global.localStorage) return;
+        global.localStorage.setItem('notifications_enabled', 'false');
+        this.forceUpdate();
+    },
+
+    enable: function() {
+        if (!this.havePermission()) {
+            global.Notification.requestPermission();
+        }
+
+        if (!global.localStorage) return;
+        global.localStorage.setItem('notifications_enabled', 'true');
+        this.forceUpdate();
+    },
+
+    onClick: function() {
+        if (!this.notificationsAvailable()) {
+            return;
+        }
+        if (!this.enabled()) {
+            this.enable();
+        } else {
+            this.disable();
+        }
+    },
+};