diff --git a/src/gui/widget/timeline-widget.hpp b/src/gui/widget/timeline-widget.hpp
index 2eaae7a14..8e40f606d 100644
--- a/src/gui/widget/timeline-widget.hpp
+++ b/src/gui/widget/timeline-widget.hpp
@@ -23,6 +23,7 @@
 /** @file timeline-widget.hpp
  ** This file defines the core component of the Lumiera GUI
  ** 
+ ** @deprecated broken since transition to GTK-3
  ** @todo needs to be reworked from ground as if 5/2015
  **       GTK-3 uses different event handling callbacks,
  **       so the existing implementation is defunct.
@@ -67,6 +68,7 @@ namespace widget {
    * Core timeline display (custom widget).
    * @remarks This widget is a composite of several widgets contained
    *          within the timeline namespace.
+   * @deprecated dysfunctional and broken by switch to GTK-3. Needs to be rewritten
    */
   class TimelineWidget
     : public Gtk::Table
diff --git a/src/gui/widget/timeline/timeline-body.hpp b/src/gui/widget/timeline/timeline-body.hpp
index d3dd39e43..f31380f0d 100644
--- a/src/gui/widget/timeline/timeline-body.hpp
+++ b/src/gui/widget/timeline/timeline-body.hpp
@@ -125,6 +125,7 @@ protected:
   
   /**
    * The event handler for when the TimelineWidget's state is switched.
+   * @deprecated needs to be rewritten from scratch for GTK-3
    */
   void on_state_changed (shared_ptr<TimelineState> newState);
   
diff --git a/src/lib/diff/gen-node.hpp b/src/lib/diff/gen-node.hpp
index 4b49ca4ae..ffb589db8 100644
--- a/src/lib/diff/gen-node.hpp
+++ b/src/lib/diff/gen-node.hpp
@@ -120,7 +120,7 @@ namespace diff{
   
   using std::string;
   
-  class GenNode;
+  struct GenNode;
   
   using Rec = Record<GenNode>;
   using RecRef = RecordRef<GenNode>;
@@ -170,7 +170,7 @@ namespace diff{
       class ID
         : public idi::BareEntryID
         {
-          friend class GenNode;
+          friend struct GenNode;
           
           template<typename X>
           ID (X*, string const& symbolicID)
diff --git a/src/lib/diff/tree-mutator.hpp b/src/lib/diff/tree-mutator.hpp
index 2e3254f3d..25e44f57a 100644
--- a/src/lib/diff/tree-mutator.hpp
+++ b/src/lib/diff/tree-mutator.hpp
@@ -75,7 +75,7 @@ namespace diff{
   
   namespace {
     template<class PAR>
-    class Builder;
+    struct Builder;
     
     using ID        = Literal;
     using Attribute = DataCap;
diff --git a/src/lib/format-string.hpp b/src/lib/format-string.hpp
index fa884b174..173ebc8b8 100644
--- a/src/lib/format-string.hpp
+++ b/src/lib/format-string.hpp
@@ -117,7 +117,7 @@
 namespace std { // forward declaration to avoid including <iostream>
   
   template<typename C>
-  class char_traits;
+  struct char_traits;
   
   template<typename C, class _TRAITS>
   class basic_ostream;
diff --git a/src/lib/iter-adapter.hpp b/src/lib/iter-adapter.hpp
index 69d5407fd..ccf36f3d5 100644
--- a/src/lib/iter-adapter.hpp
+++ b/src/lib/iter-adapter.hpp
@@ -107,7 +107,7 @@ namespace lib {
   
   
   namespace { // internal helpers
-    void
+    inline void
     _throwIterExhausted()
     {
       throw lumiera::error::Invalid ("Can't iterate further",
diff --git a/src/lib/meta/virtual-copy-support.hpp b/src/lib/meta/virtual-copy-support.hpp
index 9e1cfee30..fee8effa4 100644
--- a/src/lib/meta/virtual-copy-support.hpp
+++ b/src/lib/meta/virtual-copy-support.hpp
@@ -34,16 +34,16 @@
  ** a virtual function (which requires a VTable): Even if for everyone else any
  ** knowledge regarding the exact implementation type has been discarded ("erased"),
  ** the function pointers in the VTable still implicitly hold onto that precise
- ** implementation type, since they were setup during construction, where the
+ ** implementation type, since they were set up during construction, where the
  ** type was still available. Such a scheme of dealing with "opaque" copy operations
  ** is known as <b>virtual copy</b> -- it can be dangerous and tricky to get right
  ** and is preferably used only in flat class hierarchies.
  ** 
  ** This helper template simplifies the construction of such a scheme.
  ** - a base interface defines the available virtual copy operations
- ** - a set of CRTP-style templates covers all the case of
+ ** - a set of CRTP-style templates covers all the cases of
  **   - full copy support
- **   - copy construction but not assignment
+ **   - copy construction but no assignment
  **   - only move construction allowed
  **   - noncopyable type
  ** - we use type traits and a policy template to pick the correct implementation
@@ -144,6 +144,8 @@ namespace meta{
     : public BASE
     {
     public:
+      virtual ~VirtualCopySupportInterface()  { }
+      
       virtual void  copyInto (void* targetStorage)  const =0;
       virtual void  moveInto (void* targetStorage)        =0;
       virtual void  copyInto (IFA&         target)  const =0;
@@ -198,6 +200,9 @@ namespace meta{
           D& src = static_cast<D&> (*this);
           new(targetStorage) D(move(src));
         }
+      
+      using I::copyInto;
+      using I::moveInto;
     };
   
   
@@ -211,6 +216,9 @@ namespace meta{
           D const& src = static_cast<D const&> (*this);
           new(targetStorage) D(src);
         }
+      
+      using I::copyInto;
+      using I::moveInto;
     };
   
   
@@ -233,6 +241,9 @@ namespace meta{
           D& s = static_cast<D&> (*this);
           t = move(s);
         }
+      
+      using I::copyInto;
+      using I::moveInto;
     };
   
   
diff --git a/src/lib/variant.hpp b/src/lib/variant.hpp
index 19f272b01..9902e1746 100644
--- a/src/lib/variant.hpp
+++ b/src/lib/variant.hpp
@@ -59,6 +59,14 @@
  ** concrete type does not support assignment or copy construction, the respective access
  ** function is replaced by an implementation raising a runtime error.
  ** 
+ ** @note we use a Visitor interface generated through metaprogramming.
+ **       This may generate a lot of warnings "-Woverloaded-virtual",
+ **       since one \c handle(TX) function may shadow other \c handle(..) functions
+ **       from the inherited (generated) Visitor interface. These warnings are besides
+ **       the point, since not the \em client uses these functions, but the Variant does,
+ **       after upcasting to the interface. Make sure you define your specialisations with
+ **       the override modifier; when done so, it is safe to disable this warning here.
+ ** 
  ** @see Veriant_test
  ** @see lib::diff::GenNode
  ** @see virtual-copy-support.hpp
diff --git a/src/proc/asset/procpatt.hpp b/src/proc/asset/procpatt.hpp
index 7f61e0751..b6202085a 100644
--- a/src/proc/asset/procpatt.hpp
+++ b/src/proc/asset/procpatt.hpp
@@ -39,7 +39,7 @@ namespace asset {
   
   class Proc;
   class ProcPatt;
-  class BuildInstruct; 
+  struct BuildInstruct;
   typedef lib::P<const asset::Proc> PProc;
   typedef lib::P<const asset::ProcPatt> PProcPatt;
   
diff --git a/src/proc/asset/struct-scheme.hpp b/src/proc/asset/struct-scheme.hpp
index 350f1d090..ab5a837a5 100644
--- a/src/proc/asset/struct-scheme.hpp
+++ b/src/proc/asset/struct-scheme.hpp
@@ -48,7 +48,7 @@ using boost::format;
 
 
 namespace proc {
-  class StreamType;
+  struct StreamType;
   
 namespace mobject {
 namespace session {
diff --git a/src/proc/mobject/builder/model-port-registry.hpp b/src/proc/mobject/builder/model-port-registry.hpp
index 694e5d783..e836c2289 100644
--- a/src/proc/mobject/builder/model-port-registry.hpp
+++ b/src/proc/mobject/builder/model-port-registry.hpp
@@ -87,7 +87,7 @@ namespace builder {
     public:
       
       /** @internal record to describe a model port */
-      struct ModelPortDescriptor;
+      class ModelPortDescriptor;
       
       
       static void shutdown ();
diff --git a/src/proc/mobject/session/query/fake-configrules.hpp b/src/proc/mobject/session/query/fake-configrules.hpp
index 93058a54e..b74c18993 100644
--- a/src/proc/mobject/session/query/fake-configrules.hpp
+++ b/src/proc/mobject/session/query/fake-configrules.hpp
@@ -175,7 +175,7 @@ namespace session {
       {
         typedef typename WrapReturn<TY>::Wrapper Ret;
         
-      public:
+        
         /** (dummy) implementation of the QueryHandler interface */
         virtual bool 
         resolve (Ret& solution, Query<TY> const& q)
diff --git a/src/proc/streamtype.hpp b/src/proc/streamtype.hpp
index e357bd694..0c9c677fb 100644
--- a/src/proc/streamtype.hpp
+++ b/src/proc/streamtype.hpp
@@ -47,6 +47,10 @@ namespace proc {
   using lib::Symbol;
   
   
+// "yes mummy, we all know this code is not finished yet..."
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wuninitialized"
+  
   /**
    * TODO write type comment
    */
diff --git a/tests/basics/streamtypebasicstest.cpp b/tests/basics/streamtypebasicstest.cpp
index c0deaa898..53f8a6809 100644
--- a/tests/basics/streamtypebasicstest.cpp
+++ b/tests/basics/streamtypebasicstest.cpp
@@ -50,7 +50,7 @@ namespace test_format {
   class StreamTypeBasics_test : public Test
     {
       virtual void
-      run (Arg arg)
+      run (Arg)
         {
           ImplType iType = buildImplType ();
           basicImplTypeProperties (iType);
diff --git a/tests/core/proc/mobject/builder/model-port-registry-test.cpp b/tests/core/proc/mobject/builder/model-port-registry-test.cpp
index c769e802b..1d47fb689 100644
--- a/tests/core/proc/mobject/builder/model-port-registry-test.cpp
+++ b/tests/core/proc/mobject/builder/model-port-registry-test.cpp
@@ -161,6 +161,7 @@ namespace test  {
           CHECK (mp1);
           CHECK (mp2);
           CHECK (mp1x);
+          CHECK (mp2x);
           CHECK (!mpNull);                       // bool check verifies setup and connected state
           
           CHECK ( ModelPort::exists (pipeA));    // this is the same check, but invoked just with an pipe-ID
diff --git a/tests/library/diff/gen-node-basic-test.cpp b/tests/library/diff/gen-node-basic-test.cpp
index cac1344a4..6fe4e4ca3 100644
--- a/tests/library/diff/gen-node-basic-test.cpp
+++ b/tests/library/diff/gen-node-basic-test.cpp
@@ -198,7 +198,7 @@ namespace test{
           ++scope;
           CHECK (luid == scope->data.get<LuidH>());
           ++scope;
-          CHECK (Time(0.92,0) == scope->data.get<TimeSpan>().end());
+          CHECK (Time(920,0) == scope->data.get<TimeSpan>().end());
           ++scope;
           auto spam = *scope;
           CHECK (!++scope);