diff --git a/extension/common.js b/extension/common.js
index 12bcda6..216441c 100644
--- a/extension/common.js
+++ b/extension/common.js
@@ -3,7 +3,7 @@
 'use strict';
 
 
-const cache = {};
+const cache = {}; // cache how a tab's request get handled (true, false, object)
 const tabs = {};
 const cookieStoreIds = {};
 chrome.tabs.onRemoved.addListener(id => {
@@ -47,22 +47,35 @@ const expand = () => {
 };
 expand.rules = {};
 
+const currentCookieStoreId = () => new Promise(resolve => chrome.tabs.query({
+  active: true,
+  currentWindow: true
+}, tbs => {
+  resolve((tbs.length ? tbs[0].cookieStoreId : '') || 'firefox-default');
+}));
+
 chrome.storage.local.get(prefs, ps => {
   Object.assign(prefs, ps);
-  // update prefs.ua from the managed storage
-  chrome.storage.managed.get({
-    ua: ''
-  }, rps => {
-    if (!chrome.runtime.lastError && rps.ua) {
-      prefs.ua = rps.ua;
-    }
-    expand();
-    chrome.tabs.query({}, ts => {
-      ts.forEach(t => {
-        tabs[t.id] = t.windowId;
-        cookieStoreIds[t.id] = t.cookieStoreId;
-      });
-      ua.update();
+  expand();
+
+  chrome.tabs.query({}, ts => {
+    ts.forEach(t => {
+      tabs[t.id] = t.windowId;
+      cookieStoreIds[t.id] = t.cookieStoreId;
+    });
+
+    // update prefs.ua from the managed storage
+    chrome.storage.managed.get({
+      ua: ''
+    }, rps => {
+      if (!chrome.runtime.lastError && rps.ua) {
+        chrome.storage.local.set({
+          ua: rps.ua
+        });
+      }
+      else {
+        ua.update(undefined, undefined, 'firefox-default');
+      }
     });
   });
 
@@ -96,8 +109,17 @@ chrome.storage.local.get(prefs, ps => {
 });
 chrome.storage.onChanged.addListener(ps => {
   Object.keys(ps).forEach(key => prefs[key] = ps[key].newValue);
+
   if (ps.ua || ps.mode) {
-    ua.update();
+    currentCookieStoreId().then(cookieStoreId => {
+      if (ps.ua) {
+        if (ps.ua.newValue === '') {
+          console.log('delete from onChanged', cookieStoreId);
+          delete ua._obj[cookieStoreId];
+        }
+      }
+      ua.update(undefined, undefined, cookieStoreId);
+    });
   }
   if (ps.custom) {
     expand();
@@ -176,9 +198,8 @@ const ua = {
     log('ua.object is called', tabId, windowId, cookieStoreId);
 
     if (this._obj[cookieStoreId]) {
-      return this._obj[cookieStoreId][windowId] || this._obj[cookieStoreId].global || this._obj['default-container'].global;
+      return this._obj[cookieStoreId][windowId] || this._obj[cookieStoreId].global;
     }
-    return (this._obj['default-container'] || {}).global;
   },
   string(str, windowId, cookieStoreId) {
     log('ua.string is called', str, windowId);
@@ -219,20 +240,28 @@ const ua = {
         windowId
       }, tabs => tabs.forEach(tab => {
         const tabId = tab.id;
+        const o = ua.object(null, windowId, tab.cookieStoreId);
         chrome.browserAction.setBadgeText({
           tabId,
-          text: ua.object(null, windowId, tab.cookieStoreId).platform.substr(0, 3)
+          text: o && o.platform ? o.platform.substr(0, 3) : ''
         });
       }));
     }
     else if (tabId) {
+      const o = ua.object(tabId, undefined, cookieStoreId);
       chrome.browserAction.setBadgeText({
         tabId,
-        text: ua.object(tabId, undefined, cookieStoreId).platform.substr(0, 3)
+        text: o.platform ? o.platform.substr(0, 3) : 'BOT'
       });
     }
   },
   update(str = prefs.ua, windowId = 'global', cookieStoreId = 'default-container') {
+
+    console.log(new Error().stack, cookieStoreId);
+    console.log(str, prefs.mode === 'custom', this.windows.length, Object.keys(this._obj).length);
+
+
+
     log('ua.update is called', str, windowId, cookieStoreId);
     // clear caching
     Object.keys(cache).forEach(key => delete cache[key]);
@@ -240,8 +269,11 @@ const ua = {
     chrome.webRequest.onBeforeSendHeaders.removeListener(onBeforeSendHeaders);
     chrome.webNavigation.onCommitted.removeListener(onCommitted);
     // apply new ones
-    if (str || prefs.mode === 'custom' || this.windows.length) {
-      ua.string(str, windowId, cookieStoreId);
+    if (str || prefs.mode === 'custom' || this.windows.length || Object.keys(this._obj).length) {
+      console.log('reinstall');
+      if (str) {
+        ua.string(str, windowId, cookieStoreId);
+      }
       chrome.webRequest.onBeforeSendHeaders.addListener(onBeforeSendHeaders, {
         'urls': ['*://*/*']
       }, ['blocking', 'requestHeaders']);
@@ -266,10 +298,26 @@ const ua = {
 window.ua = ua; // using from popup
 // make sure to clean on window removal
 if (chrome.windows) { // FF on Android
+  console.log('windowId');
   chrome.windows.onRemoved.addListener(windowId => {
+    console.log(windowId, Object.keys(ua._obj), ua._obj);
+    let update = false;
     Object.keys(ua._obj).forEach(cookieStoreId => {
-      delete ua._obj[cookieStoreId][windowId];
+      if (windowId in ua._obj[cookieStoreId]) {
+        console.log('DELETE from windows', cookieStoreId);
+        delete ua._obj[cookieStoreId][windowId];
+        // delete the entire object if it is empty
+        if (Object.keys(ua._obj[cookieStoreId]).length === 0) {
+          delete ua._obj[cookieStoreId];
+        }
+        update = true;
+      }
     });
+    console.log('upda', update);
+    // if nothing is left to monitor, disable the extension
+    if (update) {
+      currentCookieStoreId().then(cookieStoreId => ua.update(undefined, undefined, cookieStoreId));
+    }
   });
 }
 
@@ -369,7 +417,6 @@ const onBeforeSendHeaders = d => {
   if (type === 'main_frame' || prefs.cache === false) {
     cache[tabId] = match({url, tabId, cookieStoreId});
   }
-  console.log(cache[tabId]);
 
   if (cache[tabId] === true) {
     return {};
@@ -377,7 +424,8 @@ const onBeforeSendHeaders = d => {
   if (prefs.protected.some(s => url.indexOf(s) !== -1)) {
     return {};
   }
-  const str = (cache[tabId] || ua.object(tabId, undefined, d.cookieStoreId)).userAgent;
+  const o = (cache[tabId] || ua.object(tabId, undefined, d.cookieStoreId));
+  const str = o ? o.userAgent : '';
   if (str) {
     for (let i = 0, name = requestHeaders[0].name; i < requestHeaders.length; i += 1, name = (requestHeaders[i] || {}).name) {
       if (name === 'User-Agent' || name === 'user-agent') {
diff --git a/extension/data/popup/index.css b/extension/data/popup/index.css
index 8c2a0b9..fb08204 100644
--- a/extension/data/popup/index.css
+++ b/extension/data/popup/index.css
@@ -190,11 +190,14 @@ select {
   background-color: #4d72b7;
   color: #fff;
 }
-[data-cmd="container"],
+[data-cmd="container"] {
+  background-color: #92773c;
+  color: #fff;
+}
 [data-cmd="window"],
 [data-cmd="apply"] {
-  color: #fff;
   background-color: #3c923c;
+  color: #fff;
 }
 
 [data-cmd="reset"] {
@@ -242,3 +245,7 @@ body[data-android="true"] [data-cmd="window"] {
 #toast:empty {
   display: none;
 }
+
+.hide {
+  visibility: hidden;
+}
diff --git a/extension/data/popup/index.html b/extension/data/popup/index.html
index 50e0e54..1d95a62 100644
--- a/extension/data/popup/index.html
+++ b/extension/data/popup/index.html
@@ -78,7 +78,7 @@
           <td>userAgent</td>
           <td colspan="3">
             <div hbox>
-              <input id="ua" type="text" placeholder="Your preferred user-agent string" title="To set a blank user-agent string, use the 'empty' keyword. To construct a custom user-agent string based on the current browser's navigator object, use ${} notation. Whatever is inside this notation is read from the 'navigator' object. For instance, to append a string to the default user-agent, use '${userAgent} THIS IS THE APPENDED STRING'">
+              <input id="ua" type="text" autofocus placeholder="Your preferred user-agent string" title="To set a blank user-agent string, use the 'empty' keyword. To construct a custom user-agent string based on the current browser's navigator object, use ${} notation. Whatever is inside this notation is read from the 'navigator' object. For instance, to append a string to the default user-agent, use '${userAgent} THIS IS THE APPENDED STRING'">
             </div>
           </td>
         </tr>
@@ -125,11 +125,11 @@
       <input type="button" value="Options" title="Open options page" style="margin-left: 2px;" data-cmd="options">
       <input type="button" value="Restart" title="Click to reload the extension. This will cause all the window-based user-agent strings to be cleared" data-cmd="reload">
       <input type="button" value="Refresh Tab" title="Refresh the current page" data-cmd="refresh">
-      <input type="button" value="Reset" title="Reset User-Agent string to the default one. This will not reset window-based UA strings. To reset them, use the 'Restart' button" data-cmd="reset">
+      <input type="button" value="Reset" title="Reset browser's user-agent string to the default one. This will not reset window-based UA strings. To reset them, use the 'Restart' button" data-cmd="reset">
       <input type="button" value="Test" title="Test your user-agent string" data-cmd="test">
-      <input type="button" value="Container" title="Set this string as this container's User-Agent string" data-cmd="container">
-      <input type="button" value="Window" title="Set this string as this window's User-Agent string" data-cmd="window">
-      <input type="button" value="Apply" title="Set this string as the browser's User-Agent string" data-cmd="apply">
+      <input type="button" value="Support Containers" title="Allow the extension to access your browser's containers. If this permission is granted, tabs inside isolated containers do not follow the default container's user-agent string. You need to set this string for each new container." data-cmd="container" class="hide">
+      <input type="button" value="Window" title="Set this user-agent string for all tabs inside the current window" data-cmd="window">
+      <input type="button" value="Apply" title="Set this user-agent string as the browser's User-Agent string" data-cmd="apply">
     </div>
     <script src="index.js"></script>
     <script async src="matched.js"></script>
diff --git a/extension/data/popup/index.js b/extension/data/popup/index.js
index d4a6baf..1b142d3 100644
--- a/extension/data/popup/index.js
+++ b/extension/data/popup/index.js
@@ -2,6 +2,30 @@
 
 document.body.dataset.android = navigator.userAgent.indexOf('Android') !== -1;
 
+let tab = {};
+
+chrome.tabs.query({
+  active: true,
+  currentWindow: true
+}, tbs => {
+  if (tbs.length) {
+    tab = tbs[0];
+    if ('cookieStoreId' in tab) {
+      const apply = document.querySelector('[data-cmd="apply"]');
+      apply.value += ' (CNT)';
+      apply.title = 'Set this user-agent string as the current container\'s User-Agent string';
+
+      const w = document.querySelector('[data-cmd="window"]');
+      w.value += ' (CNT)';
+      w.title = 'Set this user-agent string for all tabs inside the current window\'s container';
+
+      const reset = document.querySelector('[data-cmd="reset"]');
+      reset.value += ' (CNT)';
+      reset.title = 'Reset the container\'s user-agent string to the default one. This will not reset window-based UA strings. To reset them, use the \'Restart\' button';
+    }
+  }
+});
+
 const map = {};
 
 function sort(arr) {
@@ -227,37 +251,15 @@ document.addEventListener('click', ({target}) => {
       else {
         msg('User-Agent is Set');
       }
-      chrome.storage.local.set({
-        ua: '' // since we set from managed storage, the value might already be this one and hence onChanged is not being called
-      }, () => {
-        if (value !== navigator.userAgent) {
-          chrome.storage.local.set({
-            ua: value
-          });
-        }
-      });
+      if (value !== navigator.userAgent) {
+        chrome.storage.local.set({
+          ua: value
+        });
+      }
     }
-    else if (cmd === 'window' || cmd === 'container') {
+    else if (cmd === 'window') {
       const value = document.getElementById('ua').value;
-      const next = () => chrome.tabs.query({
-        active: true,
-        currentWindow: true
-      }, ([tab]) => {
-        if (cmd === 'window') {
-          chrome.runtime.getBackgroundPage(bg => bg.ua.update(value, tab.windowId, tab.cookieStoreId));
-        }
-        else {
-          chrome.runtime.getBackgroundPage(bg => bg.ua.update(value, undefined, tab.cookieStoreId));
-        }
-      });
-      if (cmd === 'container') {
-        chrome.permissions.request({
-          permissions: ['cookies']
-        }, granted => granted && next());
-      }
-      else {
-        next();
-      }
+      chrome.runtime.getBackgroundPage(bg => bg.ua.update(value, tab.windowId, tab.cookieStoreId));
     }
     else if (cmd === 'reset') {
       const input = document.querySelector('#list :checked');
@@ -267,7 +269,7 @@ document.addEventListener('click', ({target}) => {
       chrome.storage.local.set({
         ua: ''
       });
-      msg('Reset to Default');
+      msg('Disabled. Uses the default user-agent string');
     }
     else if (cmd === 'refresh') {
       chrome.tabs.query({
@@ -314,3 +316,28 @@ document.getElementById('ua').addEventListener('input', e => {
     });
   }
 });
+document.getElementById('ua').addEventListener('keyup', e => {
+  if (e.key === 'Enter') {
+    document.querySelector('[data-cmd="apply"]').click();
+  }
+});
+
+/* container support */
+document.querySelector('[data-cmd="container"]').addEventListener('click', e => {
+  chrome.permissions.request({
+    permissions: ['cookies']
+  }, granted => {
+    if (granted) {
+      e.target.classList.add('hide');
+    }
+  });
+});
+if (/Firefox/.test(navigator.userAgent)) {
+  chrome.permissions.contains({
+    permissions: ['cookies']
+  }, granted => {
+    if (granted === false) {
+      document.querySelector('[data-cmd="container"]').classList.remove('hide');
+    }
+  });
+}