diff --git a/README.md b/README.md
index 1b5e37f..def3d7d 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ For more info, see:
 ## Development
 
 1. `npm install`
-2. `./node_modules/.bin/web-ext run -s src/
+2. `./node_modules/.bin/web-ext run -s src/`
 
 ### Testing
 TBD
diff --git a/package.json b/package.json
index 5a7ff73..ca8eb7d 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "testpilot-containers",
   "title": "Multi-Account Containers",
   "description": "Containers helps you keep all the parts of your online life contained in different tabs. Custom labels and color-coded tabs help keep different activities — like online shopping, travel planning, or checking work email — separate.",
-  "version": "5.0.0",
+  "version": "5.0.1",
   "author": "Andrea Marchesini, Luke Crouch and Jonathan Kingston",
   "bugs": {
     "url": "https://github.com/mozilla/testpilot-containers/issues"
diff --git a/src/js/background/assignManager.js b/src/js/background/assignManager.js
index 7040b4f..bcc8dc2 100644
--- a/src/js/background/assignManager.js
+++ b/src/js/background/assignManager.js
@@ -132,7 +132,7 @@ const assignManager = {
 
     // The container we have in the assignment map isn't present any more so lets remove it
     //   then continue the existing load
-    if (!container) {
+    if (siteSettings && !container) {
       this.deleteContainer(siteSettings.userContextId);
       return {};
     }
@@ -147,15 +147,31 @@ const assignManager = {
       || (messageHandler.lastCreatedTab
         && messageHandler.lastCreatedTab.id === tab.id);
     const openTabId = removeTab ? tab.openerTabId : tab.id;
+    
+    // we decided to cancel the request at this point, register it as canceled request as early as possible
+    if (!this.canceledRequests[options.requestId]) {
+      this.canceledRequests[options.requestId] = true;
+      // register a cleanup for handled requestIds
+      // all relevant requests that come in that timeframe with the same requestId will be canceled
+      setTimeout(() => {
+        delete this.canceledRequests[options.requestId];
+      }, 2000);
+    } else {
+      // if we see a request for the same requestId at this point then this is a redirect that we have to cancel to prevent opening two tabs
+      return {
+        cancel: true
+      };
+    }
+    
     this.reloadPageInContainer(
-        options.url,
-        userContextId,
-        siteSettings.userContextId,
-        tab.index + 1,
-        tab.active,
-        siteSettings.neverAsk,
-        openTabId
-        );
+      options.url,
+      userContextId,
+      siteSettings.userContextId,
+      tab.index + 1,
+      tab.active,
+      siteSettings.neverAsk,
+      openTabId
+    );
     this.calculateContextMenu(tab);
 
     /* Removal of existing tabs:
@@ -183,6 +199,7 @@ const assignManager = {
     });
 
     // Before a request is handled by the browser we decide if we should route through a different container
+    this.canceledRequests = {};
     browser.webRequest.onBeforeRequest.addListener((options) => {
       return this.onBeforeRequest(options);
     },{urls: ["<all_urls>"], types: ["main_frame"]}, ["blocking"]);
diff --git a/src/js/background/backgroundLogic.js b/src/js/background/backgroundLogic.js
index 36bcb47..04906d8 100644
--- a/src/js/background/backgroundLogic.js
+++ b/src/js/background/backgroundLogic.js
@@ -131,9 +131,13 @@ const backgroundLogic = {
     let newWindowObj;
     let hiddenDefaultTabToClose;
     if (list.length) {
-      newWindowObj = await browser.windows.create({
-        tabId: list.shift().id
-      });
+      newWindowObj = await browser.windows.create();
+
+      // Pin the default tab in the new window so existing pinned tabs can be moved after it.
+      // From the docs (https://developer.mozilla.org/en-US/Add-ons/WebExtensions/API/tabs/move):
+      //   Note that you can't move pinned tabs to a position after any unpinned tabs in a window, or move any unpinned tabs to a position before any pinned tabs.
+      await browser.tabs.update(newWindowObj.tabs[0].id, { pinned: true });
+
       browser.tabs.move(list.map((tab) => tab.id), {
         windowId: newWindowObj.id,
         index: -1
diff --git a/src/js/background/messageHandler.js b/src/js/background/messageHandler.js
index 1971953..6e5fced 100644
--- a/src/js/background/messageHandler.js
+++ b/src/js/background/messageHandler.js
@@ -72,6 +72,42 @@ const messageHandler = {
       return response;
     });
 
+    // Handles external messages from webextensions
+    const externalExtensionAllowed = {};
+    browser.runtime.onMessageExternal.addListener(async (message, sender) => {
+      if (!externalExtensionAllowed[sender.id]) {
+        const extensionInfo = await browser.management.get(sender.id);
+        if (!extensionInfo.permissions.includes("contextualIdentities")) {
+          throw new Error("Missing contextualIdentities permission");
+        }
+        externalExtensionAllowed[sender.id] = true;
+      }
+      let response;
+      switch (message.method) {
+      case "getAssignment":
+        if (typeof message.url === "undefined") {
+          throw new Error("Missing message.url");
+        }
+        response = assignManager.storageArea.get(message.url);
+        break;
+      default:
+        throw new Error("Unknown message.method");
+      }
+      return response;
+    });
+    // Delete externalExtensionAllowed if add-on installs/updates; permissions might change
+    browser.management.onInstalled.addListener(extensionInfo => {
+      if (externalExtensionAllowed[extensionInfo.id]) {
+        delete externalExtensionAllowed[extensionInfo.id];
+      }
+    });
+    // Delete externalExtensionAllowed if add-on uninstalls; not needed anymore
+    browser.management.onUninstalled.addListener(extensionInfo => {
+      if (externalExtensionAllowed[extensionInfo.id]) {
+        delete externalExtensionAllowed[extensionInfo.id];
+      }
+    });
+
     if (browser.contextualIdentities.onRemoved) {
       browser.contextualIdentities.onRemoved.addListener(({contextualIdentity}) => {
         const userContextId = backgroundLogic.getUserContextIdFromCookieStoreId(contextualIdentity.cookieStoreId);
diff --git a/src/js/popup.js b/src/js/popup.js
index a644322..a9e3d26 100644
--- a/src/js/popup.js
+++ b/src/js/popup.js
@@ -524,7 +524,8 @@ Logic.registerPanel(P_CONTAINERS_LIST, {
         previous();
         break;
       default:
-        if (e.keyCode >= 49 && e.keyCode <= 57) {
+        if ((e.keyCode >= 49 && e.keyCode <= 57) &&
+            Logic._currentPanel === "containersList") {
           const element = selectables[e.keyCode - 48];
           if (element) {
             element.click();
diff --git a/src/manifest.json b/src/manifest.json
index 199f593..3963e24 100644
--- a/src/manifest.json
+++ b/src/manifest.json
@@ -1,7 +1,7 @@
 {
   "manifest_version": 2,
   "name": "Firefox Multi-Account Containers",
-  "version": "5.0.0",
+  "version": "5.0.1",
 
   "description": "Multi-Account Containers helps you keep all the parts of your online life contained in different tabs. Custom labels and color-coded tabs help keep different activities — like online shopping, travel planning, or checking work email — separate.",
   "icons": {
@@ -11,6 +11,7 @@
 
   "applications": {
     "gecko": {
+      "id": "@testpilot-containers",
       "strict_min_version": "57.0"
     }
   },
@@ -25,6 +26,7 @@
     "contextualIdentities",
     "history",
     "idle",
+    "management",
     "storage",
     "tabs",
     "webRequestBlocking",