diff --git a/src/common/singletonfactory.hpp b/src/common/singletonfactory.hpp
index 0065227df..0f6a12755 100644
--- a/src/common/singletonfactory.hpp
+++ b/src/common/singletonfactory.hpp
@@ -35,7 +35,7 @@ This code is heavily inspired by
 #define LUMIERA_SINGLETONFACTORY_H
 
 
-#include "common/singletonpolicies.hpp"  ///< several Policies usable together with SingletonFactory
+#include "common/singletonpolicies.hpp"  // several Policies usable together with SingletonFactory
 
 #include "common/util.hpp"
 #include "proc/nobugcfg.hpp"
diff --git a/src/proc/mobject/session/defsmanager.cpp b/src/proc/mobject/session/defsmanager.cpp
index b60e38064..538e8c9a8 100644
--- a/src/proc/mobject/session/defsmanager.cpp
+++ b/src/proc/mobject/session/defsmanager.cpp
@@ -35,10 +35,9 @@ using lumiera::query::QueryHandler;
 using lumiera::query::LUMIERA_ERROR_CAPABILITY_QUERY;
 
 
-namespace mobject
-  {
-  namespace session
-    {
+namespace mobject {
+  namespace session {
+  
     using lumiera::P;
     
     
@@ -51,6 +50,13 @@ namespace mobject
     }
     
     
+    
+    /** @internal causes boost::checked_delete from \c scoped_ptr<DefsRegistry>
+     *  to be placed here, where the declaration of DefsRegistry is available.*/
+    DefsManager::~DefsManager() {}
+    
+    
+    
     template<class TAR>
     P<TAR>
     DefsManager::search  (const Query<TAR>& capabilities)
diff --git a/src/proc/mobject/session/defsmanager.hpp b/src/proc/mobject/session/defsmanager.hpp
index eb2ca1502..276ed4c88 100644
--- a/src/proc/mobject/session/defsmanager.hpp
+++ b/src/proc/mobject/session/defsmanager.hpp
@@ -33,14 +33,14 @@
 
 
 
-namespace mobject
-  {
-  namespace session
-    {
+namespace mobject {
+  namespace session {
+    
+    
     using lumiera::P;
     using boost::scoped_ptr;
     
-    class DefsRegistry;
+    namespace impl { class DefsRegistry; }
 
 
     /**
@@ -55,7 +55,7 @@ namespace mobject
      */
     class DefsManager : private boost::noncopyable
       {
-        scoped_ptr<DefsRegistry> defsRegistry;
+        scoped_ptr<impl::DefsRegistry> defsRegistry;
         
       protected:
         
@@ -63,6 +63,8 @@ namespace mobject
         friend class SessManagerImpl;
         
       public:
+       ~DefsManager ();
+       
         /** common access point: retrieve the default object fulfilling
          *  some given conditions. May silently trigger object creation.
          *  @throw error::Config in case no solution is possible, which
diff --git a/src/proc/mobject/session/defsregistry.hpp b/src/proc/mobject/session/defsregistry.hpp
index 73925e11a..75068ec92 100644
--- a/src/proc/mobject/session/defsregistry.hpp
+++ b/src/proc/mobject/session/defsregistry.hpp
@@ -21,6 +21,21 @@
 */
 
 
+/** @file defsregistry.hpp
+ ** A piece of implementation code factored out into a separate header (include).
+ ** Only used in defsmanager.cpp and for the unit tests. We can't place it into
+ ** a separate compilation unit, because defsmanager.cpp defines some explicit
+ ** template instantiaton, which cause the different Slots of the DefsrRegistry#table_
+ ** to be filled with data and defaults for the specific Types.
+ ** 
+ ** @see mobject::session::DefsManager
+ ** @see defsregistryimpltest.cpp
+ **
+ */
+
+
+
+
 #ifndef MOBJECT_SESSION_DEFSREGISTRY_H
 #define MOBJECT_SESSION_DEFSREGISTRY_H
 
@@ -52,9 +67,14 @@ namespace mobject
     using boost::lambda::_1;
     using boost::lambda::var;  
     
-    namespace // Implementation details //////////////////TODO better a named implementation namespace (avoids warnings on gcc 4.3)
-//////////////////////////////////////////////////////////FIXME this is a *real* problem, because this namespace create storage, which it shouldn't      
-      {
+    namespace impl {
+      
+      namespace {
+        uint maxSlots (0); ///< number of different registered Types
+        format dumpRecord ("%2i| %64s --> %s\n");
+      }
+      
+      
       struct TableEntry 
         {
           virtual ~TableEntry() {};
@@ -64,9 +84,6 @@ namespace mobject
        *  for every participating kind of objects */
       typedef std::vector< P<TableEntry> > Table;
       
-      uint maxSlots (0); ///< number of different registered Types
-      
-      format dumpRecord ("%2i| %64s --> %s\n");
       
       /** 
        * holding a single "default object" entry 
@@ -83,13 +100,13 @@ namespace mobject
               query (q),
               objRef (obj)
             { }
-
+          
           
           struct Search  ///< Functor searching for a specific object
             {
               Search (const P<TAR>& obj)
                 : obj_(obj) { }
-
+              
               const P<TAR>& obj_;
               
               bool 
@@ -160,9 +177,9 @@ namespace mobject
       template<class TAR>
       size_t Slot<TAR>::index (0);
       
-    } // (End) impl namespace
-    
-
+      
+      
+      
     /**
      * @internal Helper for organizing preconfigured default objects.
      * Maintaines a collection of objects known or encountered as "default"
@@ -315,9 +332,14 @@ namespace mobject
             return res;
           }
       };
-
       
-
+      
+      
+    } // (End) impl namespace
+    
+    using impl::DefsRegistry;
+    
+    
   } // namespace mobject::session
 
 } // namespace mobject
diff --git a/src/proc/mobject/session/session.cpp b/src/proc/mobject/session/session.cpp
index 5c4bb8592..d8d20ed4c 100644
--- a/src/proc/mobject/session/session.cpp
+++ b/src/proc/mobject/session/session.cpp
@@ -32,9 +32,8 @@
 
 
 #include "proc/mobject/session.hpp"
-#include "proc/mobject/session/sessionimpl.hpp"
 #include "proc/mobject/session/defsmanager.hpp"
-#include "proc/mobject/session/defsregistry.hpp"
+#include "proc/mobject/session/sessionimpl.hpp"
 
 #include "common/singleton.hpp"
 
diff --git a/src/proc/mobject/session/sessionimpl.hpp b/src/proc/mobject/session/sessionimpl.hpp
index 89e3c020a..a56fdb217 100644
--- a/src/proc/mobject/session/sessionimpl.hpp
+++ b/src/proc/mobject/session/sessionimpl.hpp
@@ -94,6 +94,8 @@ namespace mobject
         friend class lumiera::singleton::StaticCreate<SessManagerImpl>;
         
       public:
+        virtual ~SessManagerImpl() {}
+        
         virtual void clear () ;
         virtual void reset () ;
         virtual void load ()  ;
diff --git a/src/proc/mobject/session/sessmanagerimpl.cpp b/src/proc/mobject/session/sessmanagerimpl.cpp
index 8195e4fbe..7ac96bee4 100644
--- a/src/proc/mobject/session/sessmanagerimpl.cpp
+++ b/src/proc/mobject/session/sessmanagerimpl.cpp
@@ -39,7 +39,7 @@
 #include "proc/mobject/session.hpp"
 #include "proc/mobject/session/sessionimpl.hpp"
 #include "proc/mobject/session/defsmanager.hpp"
-#include "proc/mobject/session/defsregistry.hpp"
+//#include "proc/mobject/session/defsregistry.hpp"
 #include "common/error.hpp"
 
 using boost::scoped_ptr;