diff -r 000000000000 -r 6474c204b198 addon-sdk/source/examples/library-detector/lib/main.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/addon-sdk/source/examples/library-detector/lib/main.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,67 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const tabs = require('sdk/tabs');
+const widgets = require('sdk/widget');
+const data = require('sdk/self').data;
+const pageMod = require('sdk/page-mod');
+const panel = require('sdk/panel');
+
+const ICON_WIDTH = 16;
+
+function updateWidgetView(tab) {
+  let widgetView = widget.getView(tab.window);
+  if (!tab.libraries) {
+    tab.libraries = [];
+  }
+  widgetView.port.emit("update", tab.libraries);
+  widgetView.width = tab.libraries.length * ICON_WIDTH;
+}
+
+var widget = widgets.Widget({
+  id: "library-detector",
+  label: "Library Detector",
+  contentURL: data.url("widget.html"),
+  panel: panel.Panel({
+    width: 240,
+    height: 60,
+    contentURL: data.url("panel.html")
+  })
+});
+
+widget.port.on('setLibraryInfo', function(libraryInfo) {
+  widget.panel.postMessage(libraryInfo);
+});
+
+pageMod.PageMod({
+  include: "*",
+  contentScriptWhen: 'end',
+  contentScriptFile: (data.url('library-detector.js')),
+  onAttach: function(worker) {
+    worker.on('message', function(libraryList) {
+      if (!worker.tab.libraries) {
+        worker.tab.libraries = [];
+      }
+      libraryList.forEach(function(library) {
+        if (worker.tab.libraries.indexOf(library) == -1) {
+          worker.tab.libraries.push(library);
+        }
+      });
+      if (worker.tab == tabs.activeTab) {
+        updateWidgetView(worker.tab);
+      }
+    });
+  }
+});
+
+tabs.on('activate', function(tab) {
+  updateWidgetView(tab);
+});
+
+/*
+For change of location
+*/
+tabs.on('ready', function(tab) {
+  tab.libraries = [];
+});
\ No newline at end of file