Retain global page components between routes

js/lib/components/AlertManager.js

@@ -24,6 +24,13 @@ export default class AlertManager extends Component {
     );
   }
 
+  config(isInitialized, context) {
+    // Since this component is 'above' the content of the page (that is, it is a
+    // part of the global UI that persists between routes), we will flag the DOM
+    // to be retained across route changes.
+    context.retain = true;
+  }
+
   /**
    * Show an Alert in the alerts area.
    *