From 23bef68a8f0a3f08ff3a5d22646c26c41a8dbffa Mon Sep 17 00:00:00 2001
From: Richard Lewis <richard@smetco.co.uk>
Date: Thu, 18 Jan 2018 13:16:06 +0000
Subject: [PATCH] Fix duplicate message listeners

---
 src/WidgetMessaging.js                   | 16 ++++++++++++----
 src/components/views/elements/AppTile.js |  8 ++------
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/src/WidgetMessaging.js b/src/WidgetMessaging.js
index cd1e4a0996..c1af402e4d 100644
--- a/src/WidgetMessaging.js
+++ b/src/WidgetMessaging.js
@@ -178,6 +178,10 @@ export default class WidgetMessaging extends MatrixPostMessageApi {
     constructor(widgetId, targetWindow) {
         super(targetWindow);
         this.widgetId = widgetId;
+
+        this.startListening = this.startListening.bind(this);
+        this.stopListening = this.stopListening.bind(this);
+        this.onMessage = this.onMessage.bind(this);
     }
 
     exec(action) {
@@ -206,9 +210,11 @@ export default class WidgetMessaging extends MatrixPostMessageApi {
      * Register widget message event listeners
      */
     startListening() {
-        this.start();
         if (global.mxWidgetMessagingListenerCount === 0) {
-            window.addEventListener("message", (evt) => this.onMessage(evt), false);
+            // Start postMessage API listener
+            this.start();
+            // Start widget specific listener
+            window.addEventListener("message", this.onMessage, false);
         }
         global.mxWidgetMessagingListenerCount += 1;
     }
@@ -217,10 +223,12 @@ export default class WidgetMessaging extends MatrixPostMessageApi {
      * De-register widget message event listeners
      */
     stopListening() {
-        this.stop();
         global.mxWidgetMessagingListenerCount -= 1;
         if (global.mxWidgetMessagingListenerCount === 0) {
-            window.removeEventListener("message", () => this.onMessage);
+            // Stop widget specific listener
+            window.removeEventListener("message", this.onMessage, false);
+            // Stop postMessage API listener
+            this.stop();
         }
         if (global.mxWidgetMessagingListenerCount < 0) {
             // Make an error so we get a stack trace
diff --git a/src/components/views/elements/AppTile.js b/src/components/views/elements/AppTile.js
index 05ea8cfa0b..582cc01a57 100644
--- a/src/components/views/elements/AppTile.js
+++ b/src/components/views/elements/AppTile.js
@@ -171,12 +171,8 @@ export default class AppTile extends React.Component {
 
         // Widget postMessage listeners
         try {
-            if (this.widgetMessaging) {
-                this.widgetMessaging.stopListening();
-                this.widgetMessaging.removeEndpoint(this.props.id, this.props.url);
-            } else {
-                console.warn('WidgetMessaging not initialised. Not stopping.');
-            }
+            this.widgetMessaging.stopListening();
+            this.widgetMessaging.removeEndpoint(this.props.id, this.props.url);
         } catch (e) {
             console.error('Failed to stop listening for widgetMessaging events', e.message);
         }