diff --git a/platform/firefox/frameModule.js b/platform/firefox/frameModule.js
index 0e5ec4c3f..07e440e9e 100644
--- a/platform/firefox/frameModule.js
+++ b/platform/firefox/frameModule.js
@@ -264,6 +264,9 @@ const contentObserver = {
         };
 
         sandbox.removeMessageListener = function() {
+            if ( !sandbox._messageListener_ ) {
+                return;
+            }
             try {
                 messager.removeMessageListener(
                     sandbox._sandboxId_,
@@ -280,6 +283,22 @@ const contentObserver = {
             sandbox._messageListener_ = null;
         };
 
+        // The goal is to have content scripts removed from web pages. This
+        // helps remove traces of uBlock from memory when disabling/removing
+        // the addon.
+        // For example, this takes care of:
+        //   https://github.com/gorhill/uBlock/commit/ea4faff383789053f423498c1f1165c403fde7c7#commitcomment-11964137
+        //   > "gets the whole selected tab flashing"
+        sandbox.shutdownSandbox = function() {
+            sandbox.removeMessageListener();
+            sandbox.addMessageListener =
+            sandbox.injectScript =
+            sandbox.removeMessageListener =
+            sandbox.sendAsyncMessage =
+            sandbox.shutdownSandbox = null;
+            messager = null;
+        };
+
         return sandbox;
     },
 
diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index 5f29da896..227d68229 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -695,10 +695,6 @@ vAPI.tabs.open = function(details) {
         return;
     }
 
-    if ( details.index === -1 ) {
-        details.index = tabBrowser.browsers.indexOf(tabBrowser.selectedBrowser) + 1;
-    }
-
     // Open in a standalone window
     if ( details.popup === true ) {
         Services.ww.openWindow(
@@ -711,6 +707,10 @@ vAPI.tabs.open = function(details) {
         return;
     }
 
+    if ( details.index === -1 ) {
+        details.index = tabBrowser.browsers.indexOf(tabBrowser.selectedBrowser) + 1;
+    }
+
     tab = tabBrowser.loadOneTab(details.url, { inBackground: !details.active });
 
     if ( details.index !== undefined ) {
@@ -1381,6 +1381,15 @@ vAPI.messaging.setup = function(defaultHandler) {
     cleanupTasks.push(function() {
         var gmm = vAPI.messaging.globalMessageManager;
 
+        gmm.broadcastAsyncMessage(
+            location.host + ':broadcast',
+            JSON.stringify({
+                broadcast: true,
+                channelName: 'vAPI',
+                msg: { cmd: 'shutdownSandbox' }
+            })
+        );
+
         gmm.removeDelayedFrameScript(vAPI.messaging.frameScript);
         gmm.removeMessageListener(
             location.host + ':background',
diff --git a/platform/firefox/vapi-client.js b/platform/firefox/vapi-client.js
index 62fa77e07..0bdf61731 100644
--- a/platform/firefox/vapi-client.js
+++ b/platform/firefox/vapi-client.js
@@ -19,7 +19,7 @@
     Home: https://github.com/gorhill/uBlock
 */
 
-/* global addMessageListener, removeMessageListener, sendAsyncMessage */
+/* global addMessageListener, removeMessageListener, sendAsyncMessage, shutdownSandbox */
 
 // For non background pages
 
@@ -76,32 +76,43 @@ vAPI.messaging = {
         messagingConnector(JSON.parse(msg));
     },
 
-    setup: function() {
-        addMessageListener(this.connector);
-        this.connected = true;
-        this.channels['vAPI'] = new MessagingChannel('vAPI', function(msg) {
-            if ( msg.cmd === 'injectScript' ) {
-                var details = msg.details;
-                if ( !details.allFrames && window !== window.top ) {
-                    return;
-                }
-                // TODO: investigate why this happens, and if this happens
-                // legitimately (content scripts not injected I suspect, so
-                // that would make this legitimate).
-                // Case: open popup UI from icon in uBlock's logger
-                if ( typeof self.injectScript === 'function' )  {
-                    self.injectScript(details.file);
-                }
+    builtinChannelHandler: function(msg) {
+        if ( msg.cmd === 'injectScript' ) {
+            var details = msg.details;
+            if ( !details.allFrames && window !== window.top ) {
+                return;
             }
-        });
+            // TODO: investigate why this happens, and if this happens
+            // legitimately (content scripts not injected I suspect, so
+            // that would make this legitimate).
+            // Case: open popup UI from icon in uBlock's logger
+            if ( typeof self.injectScript === 'function' )  {
+                self.injectScript(details.file);
+            }
+            return;
+        }
+        if ( msg.cmd === 'shutdownSandbox' ) {
+            vAPI.shutdown.exec();
+            vAPI.messaging.close();
+            window.removeEventListener('pagehide', vAPI.messaging.toggleListener, true);
+            window.removeEventListener('pageshow', vAPI.messaging.toggleListener, true);
+            vAPI.messaging = null;
+            vAPI = {};
+            shutdownSandbox();
+            return;
+        }
+    },
+
+    setup: function() {
+        this.channels['vAPI'] = new MessagingChannel('vAPI', this.builtinChannelHandler);
+        window.addEventListener('pagehide', this.toggleListener, true);
+        window.addEventListener('pageshow', this.toggleListener, true);
     },
 
     close: function() {
-        if ( !this.connected ) {
-            return;
-        }
-        removeMessageListener();
-        this.connected = false;
+        window.removeEventListener('pagehide', this.toggleListener, true);
+        window.removeEventListener('pageshow', this.toggleListener, true);
+        this.disconnect();
         this.channels = {};
         this.pending = {};
     },
@@ -120,25 +131,36 @@ vAPI.messaging = {
         return channel;
     },
 
+    connect: function() {
+        if ( !this.connected ) {
+            addMessageListener(this.connector);
+            this.connected = true;
+        }
+    },
+
+    disconnect: function() {
+        if ( this.connected ) {
+            removeMessageListener();
+            this.connected = false;
+        }
+    },
+
     toggleListener: function({type, persisted}) {
-        if ( !vAPI.messaging.connected ) {
+        if ( !vAPI.messaging ) {
             return;
         }
 
         if ( type === 'pagehide' ) {
-            removeMessageListener();
+            vAPI.messaging.disconnect();
             return;
         }
 
         if ( persisted ) {
-            addMessageListener(vAPI.messaging.connector);
+            vAPI.messaging.connect();
         }
     }
 };
 
-window.addEventListener('pagehide', vAPI.messaging.toggleListener, true);
-window.addEventListener('pageshow', vAPI.messaging.toggleListener, true);
-
 /******************************************************************************/
 
 var messagingConnector = function(details) {
@@ -147,6 +169,12 @@ var messagingConnector = function(details) {
     }
 
     var messaging = vAPI.messaging;
+
+    // Sandbox might have been shutdown
+    if ( !messaging ) {
+        return;
+    }
+
     var channels = messaging.channels;
     var channel;
 
@@ -195,10 +223,7 @@ var MessagingChannel = function(name, callback) {
     this.listeners = typeof callback === 'function' ? [callback] : [];
     this.refCount = 1;
     if ( typeof callback === 'function' ) {
-        var messaging = vAPI.messaging;
-        if ( !messaging.connected ) {
-            messaging.setup();
-        }
+        vAPI.messaging.connect();
     }
 };
 
@@ -208,9 +233,7 @@ MessagingChannel.prototype.send = function(message, callback) {
 
 MessagingChannel.prototype.sendTo = function(message, toTabId, toChannel, callback) {
     var messaging = vAPI.messaging;
-    if ( !messaging.connected ) {
-        messaging.setup();
-    }
+    messaging.connect();
     var auxProcessId;
     if ( callback ) {
         auxProcessId = messaging.auxProcessId++;
@@ -241,10 +264,7 @@ MessagingChannel.prototype.addListener = function(callback) {
         throw new Error('Duplicate listener.');
     }
     this.listeners.push(callback);
-    var messaging = vAPI.messaging;
-    if ( !messaging.connected ) {
-        messaging.setup();
-    }
+    vAPI.messaging.connect();
 };
 
 MessagingChannel.prototype.removeListener = function(callback) {
@@ -278,6 +298,10 @@ MessagingChannel.prototype.sendToListeners = function(msg) {
 
 /******************************************************************************/
 
+vAPI.messaging.setup();
+
+/******************************************************************************/
+
 // No need to have vAPI client linger around after shutdown if
 // we are not a top window (because element picker can still
 // be injected in top window).