diff --git a/browser/base/content/sanitize.js b/browser/base/content/sanitize.js
index 54bf72f131c..31f22438a61 100644
--- a/browser/base/content/sanitize.js
+++ b/browser/base/content/sanitize.js
@@ -204,24 +204,13 @@ Sanitizer.prototype = {
     offlineApps: {
       clear: function ()
       {
-        const Cc = Components.classes;
-        const Ci = Components.interfaces;
-        var cacheService = Cc["@mozilla.org/network/cache-service;1"].
-                           getService(Ci.nsICacheService);
-        try {
-          // Offline app data is "timeless", and doesn't respect
-          // the setting of timespan, it always clears everything
-          cacheService.evictEntries(Ci.nsICache.STORE_OFFLINE);
-        } catch(er) {}
-
-        var storageManagerService = Cc["@mozilla.org/dom/storagemanager;1"].
-                                    getService(Ci.nsIDOMStorageManager);
-        storageManagerService.clearOfflineApps();
+        Components.utils.import("resource:///modules/offlineAppCache.jsm");
+        OfflineAppCacheHelper.clear();
       },
 
       get canClear()
       {
-          return true;
+        return true;
       }
     },
 
diff --git a/browser/components/preferences/advanced.js b/browser/components/preferences/advanced.js
index 3d2c0f1750e..c12ec4b4a81 100644
--- a/browser/components/preferences/advanced.js
+++ b/browser/components/preferences/advanced.js
@@ -68,7 +68,8 @@ var gAdvancedPane = {
 #ifdef MOZ_CRASHREPORTER
     this.initSubmitCrashes();
 #endif
-    this.updateActualCacheSize();
+    this.updateActualCacheSize("disk");
+    this.updateActualCacheSize("offline");
   },
 
   /**
@@ -202,18 +203,22 @@ var gAdvancedPane = {
                                            "", null);
   },
  
-  // Retrieves the amount of space currently used by disk cache
-  updateActualCacheSize: function ()
+  // Retrieves the amount of space currently used by disk or offline cache
+  updateActualCacheSize: function (device)
   {
     var visitor = {
       visitDevice: function (deviceID, deviceInfo)
       {
-        if (deviceID == "disk") {
-          var actualSizeLabel = document.getElementById("actualCacheSize");
+        if (deviceID == device) {
+          var actualSizeLabel = document.getElementById(device == "disk" ?
+                                                        "actualDiskCacheSize" :
+                                                        "actualAppCacheSize");
           var sizeStrings = DownloadUtils.convertByteUnits(deviceInfo.totalSize);
           var prefStrBundle = document.getElementById("bundlePreferences");
-          var sizeStr = prefStrBundle.getFormattedString("actualCacheSize",
-                                                          sizeStrings);
+          var sizeStr = prefStrBundle.getFormattedString(device == "disk" ?
+                                                         "actualDiskCacheSize" :
+                                                         "actualAppCacheSize",
+                                                         sizeStrings);
           actualSizeLabel.value = sizeStr;
         }
         // Do not enumerate entries
@@ -226,6 +231,7 @@ var gAdvancedPane = {
         return false;
       }
     };
+
     var cacheService =
       Components.classes["@mozilla.org/network/cache-service;1"]
                 .getService(Components.interfaces.nsICacheService);
@@ -274,11 +280,23 @@ var gAdvancedPane = {
   clearCache: function ()
   {
     var cacheService = Components.classes["@mozilla.org/network/cache-service;1"]
-                         	       .getService(Components.interfaces.nsICacheService);
+                                 .getService(Components.interfaces.nsICacheService);
     try {
       cacheService.evictEntries(Components.interfaces.nsICache.STORE_ANYWHERE);
     } catch(ex) {}
-    this.updateActualCacheSize();
+    this.updateActualCacheSize("disk");
+  },
+
+  /**
+   * Clears the application cache.
+   */
+  clearOfflineAppCache: function ()
+  {
+    Components.utils.import("resource:///modules/offlineAppCache.jsm");
+    OfflineAppCacheHelper.clear();
+
+    this.updateActualCacheSize("offline");
+    this.updateOfflineApps();
   },
 
   readOfflineNotify: function()
@@ -432,6 +450,7 @@ var gAdvancedPane = {
 
     list.removeChild(item);
     gAdvancedPane.offlineAppSelected();
+    this.updateActualCacheSize("offline");
   },
 
   // UPDATE TAB
diff --git a/browser/components/preferences/advanced.xul b/browser/components/preferences/advanced.xul
index 27f756fb76e..8d3c5b3db4c 100644
--- a/browser/components/preferences/advanced.xul
+++ b/browser/components/preferences/advanced.xul
@@ -234,12 +234,12 @@
             </hbox>
           </groupbox>
 
-          <!-- Cache/Offline apps -->
-          <groupbox id="offlineGroup">
-            <caption label="&offlineStorage.label;"/>
- 
+          <!-- Cache -->
+          <groupbox id="cacheGroup">
+            <caption label="&httpCache.label;"/>
+
             <hbox align="center">
-              <label id="actualCacheSize" flex="1"/>
+              <label id="actualDiskCacheSize" flex="1"/>
               <button id="clearCacheButton" icon="clear"
                       label="&clearCacheNow.label;" accesskey="&clearCacheNow.accesskey;"
                       oncommand="gAdvancedPane.clearCache();"/>
@@ -260,6 +260,18 @@
                        aria-labelledby="useCacheBefore cacheSize useCacheAfter"/>
               <label id="useCacheAfter" flex="1">&limitCacheSizeAfter.label;</label>
             </hbox>
+          </groupbox>
+
+          <!-- Offline apps -->
+          <groupbox id="offlineGroup">
+            <caption label="&offlineStorage2.label;"/>
+
+            <hbox align="center">
+              <label id="actualAppCacheSize" flex="1"/>
+              <button id="clearOfflineAppCacheButton" icon="clear"
+                      label="&clearOfflineAppCacheNow.label;" accesskey="&clearOfflineAppCacheNow.accesskey;"
+                      oncommand="gAdvancedPane.clearOfflineAppCache();"/>
+            </hbox>
             <hbox align="center">
               <checkbox id="offlineNotify" flex="1"
                         label="&offlineNotify.label;" accesskey="&offlineNotify.accesskey;"
@@ -272,7 +284,7 @@
             </hbox>
             <hbox>
               <vbox flex="1">
-                <label id="offlineAppsListLabel">&offlineAppsList.label;</label>
+                <label id="offlineAppsListLabel">&offlineAppsList2.label;</label>
                 <listbox id="offlineAppsList"
                          style="height: &offlineAppsList.height;;"
                          flex="1"
diff --git a/browser/locales/en-US/chrome/browser/preferences/advanced.dtd b/browser/locales/en-US/chrome/browser/preferences/advanced.dtd
index 01a0250a447..f3578b48a46 100644
--- a/browser/locales/en-US/chrome/browser/preferences/advanced.dtd
+++ b/browser/locales/en-US/chrome/browser/preferences/advanced.dtd
@@ -40,7 +40,9 @@
 <!ENTITY connectionSettings.label        "Settings…">
 <!ENTITY connectionSettings.accesskey    "e">
 
-<!ENTITY offlineStorage.label            "Offline Storage">
+<!ENTITY httpCache.label                 "Cached Web Content">
+
+<!ENTITY offlineStorage2.label           "Offline Web Content and User Data">
 
 <!-- LOCALIZATION NOTE:
   The entities limitCacheSizeBefore.label and limitCacheSizeAfter.label appear on a single
@@ -53,6 +55,8 @@
 <!ENTITY limitCacheSizeAfter.label       "MB of space">
 <!ENTITY clearCacheNow.label             "Clear Now">
 <!ENTITY clearCacheNow.accesskey         "C">
+<!ENTITY clearOfflineAppCacheNow.label   "Clear Now">
+<!ENTITY clearOfflineAppCacheNow.accesskey "N">
 <!ENTITY overrideSmartCacheSize.label    "Override automatic cache management">
 <!ENTITY overrideSmartCacheSize.accesskey "O">
 
@@ -84,7 +88,7 @@
 <!ENTITY offlineNotifyExceptions.label   "Exceptions…">
 <!ENTITY offlineNotifyExceptions.accesskey "x">
 
-<!ENTITY offlineAppsList.label           "The following websites have stored data for offline use:">
+<!ENTITY offlineAppsList2.label          "The following websites are allowed to store data for offline use:">
 <!ENTITY offlineAppsList.height          "7em">
 <!ENTITY offlineAppsListRemove.label     "Remove…">
 <!ENTITY offlineAppsListRemove.accesskey "R">
diff --git a/browser/locales/en-US/chrome/browser/preferences/preferences.properties b/browser/locales/en-US/chrome/browser/preferences/preferences.properties
index 086e270e72a..33133d8f88e 100644
--- a/browser/locales/en-US/chrome/browser/preferences/preferences.properties
+++ b/browser/locales/en-US/chrome/browser/preferences/preferences.properties
@@ -105,11 +105,18 @@ offlinepermissionstext=The following websites are not allowed to store data for
 offlinepermissionstitle=Offline Data
 
 ####Preferences::Advanced::Network
-#LOCALIZATION NOTE: The next string is for the disk usage of the http cache.
-#   e.g., "Your cache is currently using 200 MB"
+#LOCALIZATION NOTE: The next string is for the disk usage of the web content cache.
+#   e.g., "Your web content cache is currently using 200 MB"
 #   %1$S = size
 #   %2$S = unit (MB, KB, etc.)
-actualCacheSize=Your cache is currently using %1$S %2$S of disk space
+actualDiskCacheSize=Your web content cache is currently using %1$S %2$S of disk space
+
+####Preferences::Advanced::Network
+#LOCALIZATION NOTE: The next string is for the disk usage of the application cache.
+#   e.g., "Your application cache is currently using 200 MB"
+#   %1$S = size
+#   %2$S = unit (MB, KB, etc.)
+actualAppCacheSize=Your application cache is currently using %1$S %2$S of disk space
 
 syncUnlink.title=Do you want to unlink your device?
 syncUnlink.label=This device will no longer be associated with your Sync account. All of your personal data, both on this device and in your Sync account, will remain intact.
diff --git a/browser/modules/Makefile.in b/browser/modules/Makefile.in
index e6ce990b2eb..e093d192fa4 100644
--- a/browser/modules/Makefile.in
+++ b/browser/modules/Makefile.in
@@ -51,6 +51,7 @@ endif
 EXTRA_JS_MODULES = \
 	openLocationLastURL.jsm \
 	NetworkPrioritizer.jsm \
+	offlineAppCache.jsm \
 	$(NULL)
 
 ifeq ($(MOZ_WIDGET_TOOLKIT),windows) 
diff --git a/browser/modules/offlineAppCache.jsm b/browser/modules/offlineAppCache.jsm
new file mode 100644
index 00000000000..a52d9b34459
--- /dev/null
+++ b/browser/modules/offlineAppCache.jsm
@@ -0,0 +1,54 @@
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is mozilla.org code.
+ *
+ * The Initial Developer of the Original Code is Mozilla Foundation.
+ * Portions created by the Initial Developer are Copyright (C) 2011
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Honza Bambas <honzab.moz@firemni.cz>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+ 
+let EXPORTED_SYMBOLS = ["OfflineAppCacheHelper"];
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+let OfflineAppCacheHelper = {
+  clear: function() {
+    var cacheService = Cc["@mozilla.org/network/cache-service;1"].
+                       getService(Ci.nsICacheService);
+    try {
+      cacheService.evictEntries(Ci.nsICache.STORE_OFFLINE);
+    } catch(er) {}
+
+    var storageManagerService = Cc["@mozilla.org/dom/storagemanager;1"].
+                                getService(Ci.nsIDOMStorageManager);
+    storageManagerService.clearOfflineApps();
+  }
+};