From cf47bdc4c8e446987d37adb618f79e101dfac8a6 Mon Sep 17 00:00:00 2001
From: gorhill <rhill@raymondhill.net>
Date: Tue, 29 Mar 2016 11:37:19 -0400
Subject: [PATCH] this tentatively fixes #1514

---
 platform/firefox/frameScript.js | 40 +++++++++++----------------------
 1 file changed, 13 insertions(+), 27 deletions(-)

diff --git a/platform/firefox/frameScript.js b/platform/firefox/frameScript.js
index 55e0757ce..4e09fdcbb 100644
--- a/platform/firefox/frameScript.js
+++ b/platform/firefox/frameScript.js
@@ -24,44 +24,30 @@
 // https://developer.mozilla.org/en-US/Firefox/Multiprocess_Firefox/Frame_script_environment
 
 (function() {
-
     'use strict';
 
-    if ( !this.docShell ) {
-        return;
-    }
-
     let {LocationChangeListener} = Components.utils.import(
         Components.stack.filename.replace('Script', 'Module'),
         null
     );
 
     // https://github.com/gorhill/uBlock/issues/1444
-    // Apparently the same context is used for all extensions, hence we must
-    // use scoped variables to ensure no collision.
-    let locationChangeListener;
+    // Apparently, on older versions of Firefox (31 and less), the same context
+    // is used for all extensions, hence we must use a unique variable name to
+    // ensure no collision.
+    this.ublock0LocationChangeListener = null;
 
-    // https://developer.mozilla.org/en-US/Add-ons/Code_snippets/Progress_Listeners
-    // "Note that the browser uses a weak reference to your listener object,
-    // "so make sure to keep an external reference to your object to ensure
-    // "that it stays in memory."
-    // This listener below allows us to keep `locationChangeListener` alive
-    // until we no longer need it.
-    let shutdown = function(ev) {
-        if ( ev.target === this ) {
-            this.removeEventListener('unload', shutdown);
-            locationChangeListener = null;
+    // https://github.com/gorhill/uBlock/issues/1514
+    // Fix?
+    if ( this.docShell ) {
+        let webProgress = this.docShell
+                              .QueryInterface(Components.interfaces.nsIInterfaceRequestor)
+                              .getInterface(Components.interfaces.nsIWebProgress);
+        let domWindow = webProgress.DOMWindow;
+        if ( domWindow === domWindow.top ) {
+            this.ublock0LocationChangeListener = new LocationChangeListener(this.docShell, webProgress);
         }
-    };
-    this.addEventListener('unload', shutdown);
-
-    let webProgress = this.docShell
-                          .QueryInterface(Components.interfaces.nsIInterfaceRequestor)
-                          .getInterface(Components.interfaces.nsIWebProgress);
-    if ( webProgress && webProgress.isTopLevel ) {
-        locationChangeListener = new LocationChangeListener(this.docShell, webProgress);
     }
-
 }).call(this);
 
 /******************************************************************************/