diff --git a/index.js b/index.js
index e1cd577..be2bb05 100644
--- a/index.js
+++ b/index.js
@@ -1,8 +1,12 @@
 /* global require */
 const {ContextualIdentityService} = require('resource://gre/modules/ContextualIdentityService.jsm');
+const { Cc, Ci, Cu, Cr } = require('chrome');
+
+Cu.import("resource://gre/modules/Services.jsm");
 
 const tabs = require('sdk/tabs');
 const webExtension = require('sdk/webextension');
+const { viewFor } = require("sdk/view/core");
 
 /* Let's start enabling Containers */
 var prefs = [
@@ -17,63 +21,26 @@ prefs.forEach((pref) => {
   prefService.set(pref[0], pref[1]);
 });
 
-const CONTAINER_STORE = 'firefox-container-';
-
 const identitiesState = {
 };
 
-function getCookieStoreIdForContainer(containerId) {
-  return CONTAINER_STORE + containerId;
-}
-
 function convert(identity) {
-  const cookieStoreId = getCookieStoreIdForContainer(identity.userContextId);
   let hiddenTabUrls = [];
 
-  if (cookieStoreId in identitiesState) {
-    hiddenTabUrls = identitiesState[cookieStoreId].hiddenTabUrls;
+  if (identity.userContextId in identitiesState) {
+    hiddenTabUrls = identitiesState[identity.userContextId].hiddenTabUrls;
   }
   const result = {
     name: ContextualIdentityService.getUserContextLabel(identity.userContextId),
     icon: identity.icon,
     color: identity.color,
-    cookieStoreId: cookieStoreId,
+    userContextId: identity.userContextId,
     hiddenTabUrls: hiddenTabUrls
   };
 
   return result;
 }
 
-function isContainerCookieStoreId(storeId) {
-  return storeId !== null && storeId.startsWith(CONTAINER_STORE);
-}
-
-function getContainerForCookieStoreId(storeId) {
-  if (!isContainerCookieStoreId(storeId)) {
-    return null;
-  }
-
-  const containerId = storeId.substring(CONTAINER_STORE.length);
-
-  if (ContextualIdentityService.getIdentityFromId(containerId)) {
-    return parseInt(containerId, 10);
-  }
-
-  return null;
-}
-
-function getContainer(cookieStoreId) {
-  const containerId = getContainerForCookieStoreId(cookieStoreId);
-
-  if (!containerId) {
-    return Promise.resolve(null);
-  }
-
-  const identity = ContextualIdentityService.getIdentityFromId(containerId);
-
-  return Promise.resolve(convert(identity));
-}
-
 function queryContainers(details) {
   const identities = [];
 
@@ -86,64 +53,20 @@ function queryContainers(details) {
     const convertedIdentity = convert(identity);
 
     identities.push(convertedIdentity);
-    if (!(convertedIdentity.cookieStoreId in identitiesState)) {
-      identitiesState[convertedIdentity.cookieStoreId] = {hiddenTabUrls: []};
+    if (!(convertedIdentity.userContextId in identitiesState)) {
+      identitiesState[convertedIdentity.userContextId] = {hiddenTabUrls: []};
     }
   });
 
   return Promise.resolve(identities);
 }
 
-function createContainer(details) {
-  const identity = ContextualIdentityService.create(details.name,
-                                                  details.icon,
-                                                  details.color);
-
-  return Promise.resolve(convert(identity));
-}
-
-function updateContainer(cookieStoreId, details) {
-  const containerId = getContainerForCookieStoreId(cookieStoreId);
-
-  if (!containerId) {
+function removeContainer(userContextId) {
+  if (!userContextId) {
     return Promise.resolve(null);
   }
 
-  const identity = ContextualIdentityService.getIdentityFromId(containerId);
-
-  if (!identity) {
-    return Promise.resolve(null);
-  }
-
-  if (details.name !== null) {
-    identity.name = details.name;
-  }
-
-  if (details.color !== null) {
-    identity.color = details.color;
-  }
-
-  if (details.icon !== null) {
-    identity.icon = details.icon;
-  }
-
-  if (!ContextualIdentityService.update(identity.userContextId,
-                                        identity.name, identity.icon,
-                                        identity.color)) {
-    return Promise.resolve(null);
-  }
-
-  return Promise.resolve(convert(identity));
-}
-
-function removeContainer(cookieStoreId) {
-  const containerId = getContainerForCookieStoreId(cookieStoreId);
-
-  if (!containerId) {
-    return Promise.resolve(null);
-  }
-
-  const identity = ContextualIdentityService.getIdentityFromId(containerId);
+  const identity = ContextualIdentityService.getIdentityFromId(userContextId);
 
   if (!identity) {
     return Promise.resolve(null);
@@ -159,44 +82,82 @@ function removeContainer(cookieStoreId) {
   return Promise.resolve(convertedIdentity);
 }
 
-const contextualIdentities = {
-  get: getContainer,
-  query: queryContainers,
-  create: createContainer,
-  update: updateContainer,
-  remove: removeContainer
-};
+function openTab(args) {
+  let browserWin = Services.wm.getMostRecentWindow('navigator:browser');
+
+  // This should not really happen.
+  if (!browserWin || !browserWin.gBrowser) {
+    return Promise.resolve(false);
+  }
+
+  let userContextId = 0;
+  if ('userContextId' in args) {
+    userContextId = args.userContextId;
+  }
+
+  let tab = browserWin.gBrowser.addTab(args.url || null,
+                                       { userContextId: userContextId })
+  browserWin.gBrowser.selectedTab = tab;
+  return Promise.resolve(true);
+}
+
+function queryTabs(args) {
+  return new Promise((resolve, reject) => {
+    let tabList = [];
+
+    for (let tab of tabs) {
+      let xulTab = viewFor(tab);
+      let userContextId = parseInt(xulTab.getAttribute('usercontextid') || 0, 10);
+
+      if ("userContextId" in args && args.userContextId != userContextId) {
+        continue;
+      }
+
+      tabList.push({
+        id: tab.id,
+        url: tab.url,
+        userContextId: userContextId,
+      });
+    }
+
+    resolve(tabList);
+  });
+}
+
+function removeTabs(ids) {
+  for (let tab of tabs) {
+    if (ids.indexOf(tab.id) != -1) {
+      tab.close();
+    }
+  }
+
+  return Promise.resolve(null);
+}
 
 function handleWebExtensionMessage(message, sender, sendReply) {
   switch (message.method) {
-      case 'query':
-        sendReply(contextualIdentities.query(message.arguments));
+      case 'queryIdentities':
+        sendReply(queryContainers(message.arguments));
         break;
-      case 'hide':
-        identitiesState[message.cookieStoreId].hiddenTabUrls = message.tabUrlsToSave;
+      case 'queryTabs':
+        sendReply(queryTabs(message));
         break;
-      case 'show':
-        sendReply(identitiesState[message.cookieStoreId].hiddenTabUrls);
-        identitiesState[message.cookieStoreId].hiddenTabUrls = [];
+      case 'hideTabs':
+        identitiesState[message.userContextId].hiddenTabUrls = message.tabUrlsToSave;
         break;
-      case 'get':
-        sendReply(contextualIdentities.get(message.arguments));
+      case 'showTabs':
+        sendReply(identitiesState[message.userContextId].hiddenTabUrls);
+        identitiesState[message.userContextId].hiddenTabUrls = [];
         break;
-      case 'create':
-        sendReply(contextualIdentities.create(message.arguments));
-        break;
-      case 'update':
-        sendReply(contextualIdentities.update(message.arguments));
-        break;
-      case 'remove':
-        sendReply(contextualIdentities.remove(message.arguments));
+      case 'removeTabs':
+        sendReply(removeTabs(message.tabIds));
+        identitiesState[message.userContextId].hiddenTabUrls = [];
         break;
       case 'getIdentitiesState':
         sendReply(identitiesState);
         break;
-      case 'open-containers-preferences':
-        tabs.open('about:preferences#containers');
-        sendReply({content: 'opened'});
+      case 'openTab':
+        sendReply(openTab(message));
         break;
   }
 }
diff --git a/webextension/js/popup.js b/webextension/js/popup.js
index fb3fbd2..b987c53 100644
--- a/webextension/js/popup.js
+++ b/webextension/js/popup.js
@@ -2,38 +2,45 @@
 const CONTAINER_HIDE_SRC = '/img/container-hide.svg';
 const CONTAINER_UNHIDE_SRC = '/img/container-unhide.svg';
 
-function hideContainerTabs(containerId) {
+function hideContainerTabs(userContextId) {
   const tabIdsToRemove = [];
   const tabUrlsToSave = [];
-  const hideorshowIcon = document.querySelector(`#${containerId}-hideorshow-icon`);
+  const hideorshowIcon = document.querySelector(`#uci-${userContextId}-hideorshow-icon`);
 
-  browser.tabs.query({cookieStoreId: containerId}).then(tabs=> {
+  browser.runtime.sendMessage({
+    method: 'queryTabs',
+    userContextId: userContextId
+  }).then(tabs=> {
     tabs.forEach(tab=> {
       tabIdsToRemove.push(tab.id);
       tabUrlsToSave.push(tab.url);
     });
     browser.runtime.sendMessage({
-      method: 'hide',
-      cookieStoreId: containerId,
+      method: 'hideTabs',
+      userContextId: userContextId,
       tabUrlsToSave: tabUrlsToSave
     }).then(()=> {
-      browser.tabs.remove(tabIdsToRemove);
+      browser.runtime.sendMessage({
+        method: 'removeTabs',
+        tabIds: tabIdsToRemove
+      });
       hideorshowIcon.src = CONTAINER_UNHIDE_SRC;
     });
   });
 }
 
-function showContainerTabs(containerId) {
-  const hideorshowIcon = document.querySelector(`#${containerId}-hideorshow-icon`);
+function showContainerTabs(userContextId) {
+  const hideorshowIcon = document.querySelector(`#uci-${userContextId}-hideorshow-icon`);
 
   browser.runtime.sendMessage({
-    method: 'show',
-    cookieStoreId: containerId
+    method: 'showTabs',
+    userContextId: userContextId
   }).then(hiddenTabUrls=> {
     hiddenTabUrls.forEach(url=> {
-      browser.tabs.create({
-        url: url,
-        cookieStoreId: containerId
+      browser.runtime.sendMessage({
+        method: 'openTab',
+        userContextId: userContextId,
+        url: url
       });
     });
   });
@@ -67,7 +74,7 @@ document.querySelector('#onboarding-done-button').addEventListener('click', ()=>
   document.querySelector('#container-panel').classList.remove('hide');
 });
 
-browser.runtime.sendMessage({method: 'query'}).then(identities=> {
+browser.runtime.sendMessage({method: 'queryIdentities'}).then(identities=> {
   const identitiesListElement = document.querySelector('.identities-list');
 
   identities.forEach(identity=> {
@@ -77,7 +84,7 @@ browser.runtime.sendMessage({method: 'query'}).then(identities=> {
       hideOrShowIconSrc = CONTAINER_UNHIDE_SRC;
     }
     const identityRow = `
-    <tr data-identity-cookie-store-id="${identity.cookieStoreId}" >
+    <tr data-identity-cookie-store-id="${identity.userContextId}" >
       <td>
         <div class="userContext-icon"
           data-identity-icon="${identity.icon}"
@@ -94,8 +101,8 @@ browser.runtime.sendMessage({method: 'query'}).then(identities=> {
       <td class="hideorshow" >
         <img
           title="Hide or show ${identity.name} container tabs"
-          data-identity-cookie-store-id="${identity.cookieStoreId}"
-          id="${identity.cookieStoreId}-hideorshow-icon"
+          data-identity-cookie-store-id="${identity.userContextId}"
+          id="uci-${identity.userContextId}-hideorshow-icon"
           class="icon hideorshow-icon"
           src="${hideOrShowIconSrc}"
         />
@@ -110,18 +117,18 @@ browser.runtime.sendMessage({method: 'query'}).then(identities=> {
 
   rows.forEach(row=> {
     row.addEventListener('click', e=> {
-      const containerId = e.target.parentElement.parentElement.dataset.identityCookieStoreId;
+      const userContextId = e.target.parentElement.parentElement.dataset.identityCookieStoreId;
 
       if (e.target.matches('.hideorshow-icon')) {
         browser.runtime.sendMessage({method: 'getIdentitiesState'}).then(identitiesState=> {
-          if (identitiesState[containerId].hiddenTabUrls.length) {
-            showContainerTabs(containerId);
+          if (identitiesState[userContextId].hiddenTabUrls.length) {
+            showContainerTabs(userContextId);
           } else {
-            hideContainerTabs(containerId);
+            hideContainerTabs(userContextId);
           }
         });
       } else if (e.target.matches('.newtab-icon')) {
-        browser.tabs.create({cookieStoreId: containerId});
+        browser.runtime.sendMessage({method: 'openTab', userContextId: userContextId});
         window.close();
       }
     });
@@ -129,7 +136,10 @@ browser.runtime.sendMessage({method: 'query'}).then(identities=> {
 });
 
 document.querySelector('#edit-containers-link').addEventListener('click', ()=> {
-  browser.runtime.sendMessage({method: 'open-containers-preferences'}).then(()=> {
+  browser.runtime.sendMessage({
+    method: 'openTab',
+    url: "about:preferences#containers"
+  }).then(()=> {
     window.close();
   });
 });
@@ -144,15 +154,15 @@ function moveTabs(sortedTabsArray) {
 }
 
 document.querySelector('#sort-containers-link').addEventListener('click', ()=> {
-  browser.runtime.sendMessage({method: 'query'}).then(identities=> {
-    identities.unshift({cookieStoreId: 'firefox-default'});
+  browser.runtime.sendMessage({method: 'queryIdentities'}).then(identities=> {
+    identities.unshift({userContextId: 0});
 
-    browser.tabs.query({}).then(tabsArray=> {
+    browser.runtime.sendMessage({method: 'queryTabs'}).then(tabsArray=> {
       const sortedTabsArray = [];
 
       identities.forEach(identity=> {
         tabsArray.forEach(tab=> {
-          if (tab.cookieStoreId === identity.cookieStoreId) {
+          if (tab.userContextId === identity.userContextId) {
             sortedTabsArray.push(tab.id);
           }
         });