Fixed regression: Clickhide functionality broken

background.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2013 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 553 matching lines @@
           FilterStorage.addFilter(Filter.fromText(msg.filters[i]));
       }
       break;
     case "add-subscription":
       openOptions(function(tab)
       {
         tab.sendMessage(msg);
       });
       break;
     case "forward":
-      tab.sendMessage(msg.payload, sendResponse);
+      if (sender.tab)
+      {
+        sender.tab.sendMessage(msg.payload, sendResponse);
+        // Return true to indicate that we want to call
+        // sendResponse asynchronously
+        return true;
+      }
       break;
     default:
       sendResponse({});
       break;
   }
 });
 
 // Show icon as page action for all tabs that already exist
 ext.windows.getAll(function(windows)
 {
@@ skipping 12 matching lines @@
   tab.sendMessage({type: "clickhide-deactivate"});
   refreshIconAndContextMenu(tab);
 });
 
 setTimeout(function()
 {
   var notificationToShow = Notification.getNextToShow();
   if (notificationToShow)
     showNotification(notificationToShow);
 }, 3 * 60 * 1000);