fixes #2422

app/models/post.rb

@@ -838,11 +838,20 @@ class Post < ActiveRecord::Base
       favorited_user_ids.map {|id| User.find(id)}
     end
 
-    def favorite_groups
+    def favorite_groups(active_id=nil)
       @favorite_groups ||= begin
-        CurrentUser.user.favorite_groups.select do |favgroup|
+        groups = []
+
+        if active_id.present?
+          active_group = FavoriteGroup.where(:id => active_id.to_i).first
+          groups << active_group if active_group && active_group.contains?(self.id)
+        end
+
+        groups += CurrentUser.user.favorite_groups.select do |favgroup|
           favgroup.contains?(self.id)
         end
+
+        groups.uniq
       end
     end
   end