diff --git a/src/lib/time/control.hpp b/src/lib/time/control.hpp
index 5422daf45..29a16023a 100644
--- a/src/lib/time/control.hpp
+++ b/src/lib/time/control.hpp
@@ -40,6 +40,17 @@
  ** of time-like entities -- be it the running time display in a GUI widget, a ruler marker
  ** which can be dragged, a modifiable selection or the animated playhead cursor.
  ** 
+ ** \par implementation notes
+ ** - the validity of a given combination of change and target is checked immediately,
+ **   when connecting to the target. Depending on the situation, the actual changes later
+ **   are subject to specific treatment (e.g. frame quantisation)
+ ** - by default time::Control is <b>not threadsafe</b>. But, as each change is basically
+ **   processed within its own call context (function invocation), parallelism is only
+ **   a concern with respect to the value finally visible within the target.
+ ** - the change notification is processed right away, after applying the change to the
+ **   target; in all cases, the effective change value is what will be propagated, \em not
+ **   the content of the target after applying the change
+ ** 
  ** @todo WIP-WIP-WIP
  **
  */
diff --git a/src/proc/play/play-service.hpp b/src/proc/play/play-service.hpp
index ee9a04188..f2b8e2d4d 100644
--- a/src/proc/play/play-service.hpp
+++ b/src/proc/play/play-service.hpp
@@ -33,6 +33,7 @@
 
 
 #include "lib/error.hpp"
+#include "include/play-facade.h"
 
 #include <boost/noncopyable.hpp>
 //#include <boost/scoped_ptr.hpp>
diff --git a/tests/40components.tests b/tests/40components.tests
index 22defbc85..aff1800f8 100644
--- a/tests/40components.tests
+++ b/tests/40components.tests
@@ -688,6 +688,11 @@ return: 0
 END
 
 
+PLANNED "Life changing time specifications with feedback" TimeControl_test  <<END
+return: 0
+END
+
+
 TEST "Quantiser API basics" QuantiserBasics_test  <<END
 return: 0
 END
diff --git a/tests/lib/time/time-control-test.cpp b/tests/lib/time/time-control-test.cpp
new file mode 100644
index 000000000..2742831ce
--- /dev/null
+++ b/tests/lib/time/time-control-test.cpp
@@ -0,0 +1,137 @@
+/*
+  TimeControl(Test)  -  mutating time entities with life connection and feedback
+
+  Copyright (C)         Lumiera.org
+    2011,               Hermann Vosseler <Ichthyostega@web.de>
+
+  This program is free software; you can redistribute it and/or
+  modify it under the terms of the GNU General Public License as
+  published by the Free Software Foundation; either version 2 of
+  the License, or (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+* *****************************************************/
+
+
+#include "lib/test/run.hpp"
+#include "lib/test/test-helper.hpp"
+#include "lib/time/timevalue.hpp"
+#include "lib/time/timequant.hpp"
+#include "lib/time/mutation.hpp"
+#include "proc/asset/meta/time-grid.hpp"
+#include "lib/util.hpp"
+
+#include <boost/lexical_cast.hpp>
+#include <iostream>
+#include <string>
+
+using boost::lexical_cast;
+using util::isnil;
+using std::cout;
+using std::endl;
+using std::string;
+
+
+namespace lib {
+namespace time{
+namespace test{
+  
+  using asset::meta::TimeGrid;
+  
+  namespace {
+    inline string
+    pop (Arg arg)
+    {
+      if (isnil (arg)) return "";
+      string entry = arg[0];
+      arg.erase (arg.begin());
+      return entry;
+    }
+  }
+  
+  
+  
+  
+  /****************************************************************
+   * @test use the time::Control to push a sequence of modifications
+   *       to various time entities; in all cases, a suitable change
+   *       should be imposed to the target and then a notification signal
+   *       should be invoked.
+   * @todo cover the cases.....
+   *       - change to a given value
+   *       - change by an offset
+   *       - change using a grid value
+   *       - apply an (grid) increment
+   */
+  class TimeControl_test : public Test
+    {
+      gavl_time_t
+      random_or_get (string arg)
+        {
+          if (isnil(arg))
+            return gavl_time_t (1 + (rand() % 100000)) * GAVL_TIME_SCALE;
+          else
+            return lexical_cast<gavl_time_t> (arg);
+        }
+      
+      struct TestValues
+        {
+          TimeVar var;
+          Duration dur;
+          TimeSpan span;
+          QuTime quant;
+          
+          TestValues (TimeValue o)
+            : var(o)
+            , dur(o)
+            , span(o, Offset(o))
+            , quant(o, "test_grid")
+            { }
+        };
+      
+      
+      virtual void
+      run (Arg arg) 
+        {
+          TimeValue o (random_or_get (pop(arg)));
+          TimeValue c (random_or_get (pop(arg)));
+          CHECK (o != c, "unsuitable testdata");
+          
+          // using a 25fps-grid, but with an time origin offset by 1/50sec
+          TimeGrid::build("test_grid", FrameRate::PAL, Time(FSecs(1,50)));
+          
+          QuTime qChange (c, "test_grid");
+          FrameNr count(qChange);
+          
+          verifyBasics();
+          runningMutations();
+        } 
+      
+      
+      void
+      verifyBasics()
+        {
+        }
+      
+      
+      void
+      runningMutations ()
+        {
+        }
+    };
+  
+  
+  /** Register this test class... */
+  LAUNCHER (TimeControl_test, "unit common");
+  
+  
+  
+}}} // namespace lib::time::test