diff --git a/library/Icinga/Session/Session.php b/library/Icinga/Session/Session.php
index c65c239f7..8682fea34 100644
--- a/library/Icinga/Session/Session.php
+++ b/library/Icinga/Session/Session.php
@@ -78,6 +78,28 @@ abstract class Session extends SessionNamespace
         return $this->namespaces[$identifier];
     }
 
+    /**
+     * Return whether the given session namespace exists
+     *
+     * @param   string      $identifier     The namespace's identifier to check
+     *
+     * @return  bool
+     */
+    public function hasNamespace($identifier)
+    {
+        return isset($this->namespaces[$identifier]);
+    }
+
+    /**
+     * Remove the given session namespace
+     *
+     * @param   string      $identifier     The identifier of the namespace to remove
+     */
+    public function removeNamespace($identifier)
+    {
+        unset($this->namespaces[$identifier]);
+    }
+
     /**
      * Clear all values and namespaces from the session cache
      */
diff --git a/library/Icinga/Session/SessionNamespace.php b/library/Icinga/Session/SessionNamespace.php
index 5770889af..e169b5093 100644
--- a/library/Icinga/Session/SessionNamespace.php
+++ b/library/Icinga/Session/SessionNamespace.php
@@ -30,11 +30,13 @@
 namespace Icinga\Session;
 
 use \Exception;
+use \ArrayIterator;
+use \IteratorAggregate;
 
 /**
  * Container for session values
  */
-class SessionNamespace
+class SessionNamespace implements IteratorAggregate
 {
     /**
      * The actual values stored in this container
@@ -43,6 +45,16 @@ class SessionNamespace
      */
     protected $values = array();
 
+    /**
+     * Return an iterator for all values in this namespace
+     *
+     * @return  ArrayIterator
+     */
+    public function getIterator()
+    {
+        return ArrayIterator($this->values);
+    }
+
     /**
      * Set a session value by property access
      *
diff --git a/library/Icinga/Web/Controller/ActionController.php b/library/Icinga/Web/Controller/ActionController.php
index e5f4bdb82..740197d93 100644
--- a/library/Icinga/Web/Controller/ActionController.php
+++ b/library/Icinga/Web/Controller/ActionController.php
@@ -41,10 +41,10 @@ use Icinga\Util\Translator;
 use Icinga\Web\Widget\Tabs;
 use Icinga\Web\Url;
 use Icinga\Web\Notification;
-use Icinga\Logger\Logger;
-use Icinga\Web\Request;
 use Icinga\File\Pdf;
 use Icinga\Exception\ProgrammingError;
+use Icinga\Web\Session;
+use Icinga\Session\SessionNamespace;
 
 /**
  * Base class for all core action controllers
@@ -149,6 +149,31 @@ class ActionController extends Zend_Controller_Action
         return $this->windowId;
     }
 
+    /**
+     * Return a window-aware session by using the given prefix
+     *
+     * @param   string      $prefix     The prefix to use
+     *
+     * @return  SessionNamespace
+     */
+    public function getWindowSession($prefix)
+    {
+        $session = Session::getSession();
+        $windowId = $this->getWindowId();
+        $namespace = $session->getNamespace($prefix . '_' . $windowId);
+
+        if ($windowId !== 'undefined' && $session->hasNamespace($prefix . '_undefined')) {
+            // We do not have any window-id on the very first request. Now we add all values from the
+            // namespace, that has been created in this case, to the new one and remove it afterwards.
+            foreach ($session->getNamespace($prefix . '_undefined') as $name => $value) {
+                $namespace->set($name, $value);
+            }
+            $session->removeNamespace($prefix . '_undefined');
+        }
+
+        return $namespace;
+    }
+
     /**
      * Return restriction information for an eventually authenticated user
      *
diff --git a/library/Icinga/Web/Session.php b/library/Icinga/Web/Session.php
index 5fd4dc115..02b71ad00 100644
--- a/library/Icinga/Web/Session.php
+++ b/library/Icinga/Web/Session.php
@@ -30,7 +30,6 @@
 namespace Icinga\Web;
 
 use Icinga\Session\PhpSession;
-use Icinga\Session\SessionNamespace;
 use Icinga\Session\Session as BaseSession;
 use Icinga\Exception\ProgrammingError;
 
@@ -78,21 +77,4 @@ class Session
 
         return self::$session;
     }
-
-    /**
-     * Get or create a new session namespace
-     *
-     * @param   string      $identifier     The namespace's identifier
-     *
-     * @return  SessionNamespace
-     * @throws  ProgrammingError
-     */
-    public static function getNamespace($identifier)
-    {
-        if (self::$session === null) {
-            throw new ProgrammingError('No session created yet');
-        }
-
-        return self::$session->getNamespace($identifier);
-    }
 }