diff --git a/include/osgGA/GUIEventHandlerVisitor b/include/osgGA/GUIEventHandlerVisitor
index 44c0441d4..b363ac311 100644
--- a/include/osgGA/GUIEventHandlerVisitor
+++ b/include/osgGA/GUIEventHandlerVisitor
@@ -9,6 +9,7 @@ namespace osgGA{
 
 // Some forward declarations
 class GUIActionAdapter;
+class GUIEventHandler;
 class CompositeGUIEventHandler;
 class CameraManipulator;
 class StateSetManipulator;
@@ -26,6 +27,7 @@ class OSGGA_EXPORT GUIEventHandlerVisitor
 {
     public:
 
+        virtual void visit(GUIEventHandler&) {}
         virtual void visit(CompositeGUIEventHandler&);
         virtual void visit(CameraManipulator&) {};
         virtual void visit(StateSetManipulator&) {};
diff --git a/include/osgGA/KeySwitchCameraManipulator b/include/osgGA/KeySwitchCameraManipulator
index 484f7dd29..c614fef77 100644
--- a/include/osgGA/KeySwitchCameraManipulator
+++ b/include/osgGA/KeySwitchCameraManipulator
@@ -24,17 +24,8 @@ class OSGGA_EXPORT KeySwitchCameraManipulator : public CameraManipulator
 
         void addCameraManipulator(int key, std::string name, CameraManipulator *cm);
 
-        //typedef void (* Callback)(KeySwitchCameraManipulator *);
+        void addNumberedCameraManipulator(CameraManipulator *cm);
 
-//         class Callback: public osgUtil::CallbackList<KeySwitchCameraManipulator>::Callback {
-//             public:
-//                 virtual ~Callback() {};
-//                 virtual void operator()(KeySwitchCameraManipulator *) = 0;
-//         };
-// 
-//         void addCallback(Callback*);
-// 
-//         void removeCallback(Callback*);
 
         // Overrides from CameraManipulator...
 
@@ -64,9 +55,6 @@ class OSGGA_EXPORT KeySwitchCameraManipulator : public CameraManipulator
 
         osg::ref_ptr<CameraManipulator> _current;
 
-        // Callbacks
-        //CallbackList<KeySwitchCameraManipulator>    _cameraManipChangeCallbacks;
-
 };
 
 };
diff --git a/include/osgGLUT/Viewer b/include/osgGLUT/Viewer
index e9d08fd11..d92292354 100644
--- a/include/osgGLUT/Viewer
+++ b/include/osgGLUT/Viewer
@@ -81,6 +81,8 @@ class OSGGLUT_EXPORT Viewer : public Window, public osgGA::GUIActionAdapter
         void selectCameraManipulator(unsigned int pos, 
 				     unsigned int viewport = 0);
 
+        void setEventHandler(osgGA::GUIEventHandler* handler,unsigned int viewport = 0);
+
         // derived from osgGA::GUIActionAdapter
         virtual void requestRedraw() {} // redraw always by idle callback done.
         virtual void requestContinuousUpdate(bool /*needed*/) {} // continuous update always
@@ -119,8 +121,11 @@ class OSGGLUT_EXPORT Viewer : public Window, public osgGA::GUIActionAdapter
             osg::ref_ptr<osgUtil::SceneView> sceneView;
             float viewport[4];                        // Win-size-relative [0,1]
 
-            osg::ref_ptr<osgGA::CameraManipulator>    _cameraManipulator;
+            osg::ref_ptr<osgGA::CameraManipulator>      _cameraManipulator;
             CameraManipList                             _cameraManipList;
+            
+            osg::ref_ptr<osgGA::GUIEventHandler>           _eventHandler;
+            
         };
 
         typedef std::vector<ViewportDef> ViewportList;
diff --git a/src/Demos/osgoccluder/osgoccluder.cpp b/src/Demos/osgoccluder/osgoccluder.cpp
index 99b04e974..3ba08dd7b 100644
--- a/src/Demos/osgoccluder/osgoccluder.cpp
+++ b/src/Demos/osgoccluder/osgoccluder.cpp
@@ -7,15 +7,18 @@
 #include <osg/Geode>
 #include <osg/Group>
 #include <osg/Notify>
+#include <osg/LineSegment>
 
 #include <osgDB/Registry>
 #include <osgDB/ReadFile>
+#include <osgDB/WriteFile>
 
 #include <osgGA/TrackballManipulator>
 #include <osgGA/FlightManipulator>
 #include <osgGA/DriveManipulator>
 
 #include <osgUtil/Optimizer>
+#include <osgUtil/IntersectVisitor>
 
 #include <osg/OccluderNode>
 #include <osg/Geometry>
@@ -27,6 +30,13 @@ void write_usage(std::ostream& out,const std::string& name)
     out <<"    "<<name<<" [options] infile1 [infile2 ...]"<< std::endl;
     out << std::endl;
     out <<"options:"<< std::endl;
+    out <<"    -c                  - set osgoccluder's manual mode for creating occluders."<< std::endl;
+    out <<"                          press 'a' to start/add points to an occluder, using "<< std::endl;
+    out <<"                                the nearest vertex to the current mouse poistion."<< std::endl;
+    out <<"                          press 'e' to end occluder, this occluder is then added"<< std::endl;
+    out <<"                                    into the model."<< std::endl;
+    out <<"                          press 'O' save just the occluders to disk. "<< std::endl;
+    out << std::endl;
     out <<"    -l libraryName      - load plugin of name libraryName"<< std::endl;
     out <<"                          i.e. -l osgdb_pfb"<< std::endl;
     out <<"                          Useful for loading reader/writers which can load"<< std::endl;
@@ -52,6 +62,142 @@ void write_usage(std::ostream& out,const std::string& name)
 }
 
 
+
+class OccluderEventHandler : public osgGA::GUIEventHandler
+{
+    public:
+    
+        OccluderEventHandler(osgUtil::SceneView* sceneview,osg::Group* rootnode):_sceneview(sceneview),_rootnode(rootnode) {}
+    
+        virtual bool handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter&);
+
+        virtual void accept(osgGA::GUIEventHandlerVisitor& v)
+        {
+            v.visit(*this);
+        }
+        
+        void addPoint(const osg::Vec3& pos);
+                
+        void endOccluder();
+        
+        
+        osg::ref_ptr<osgUtil::SceneView>        _sceneview;
+        osg::ref_ptr<osg::Group>                _rootnode;
+        osg::ref_ptr<osg::Group>                _occluders;
+        osg::ref_ptr<osg::ConvexPlanerOccluder> _convexPlanerOccluder;
+};
+
+bool OccluderEventHandler::handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter&)
+{
+    switch(ea.getEventType())
+    {
+        case(osgGA::GUIEventAdapter::KEYBOARD):
+        {
+            if (ea.getKey()=='a')
+            {
+
+                int x = ea.getX();
+                int y = ea.getY();
+ 
+                osg::Vec3 near_point,far_point;
+                if (!_sceneview->projectWindowXYIntoObject(x,ea.getYmax()-y,near_point,far_point))
+                {
+                     return true;
+                }
+
+                osg::ref_ptr<osg::LineSegment> lineSegment = osgNew osg::LineSegment;
+                lineSegment->set(near_point,far_point);
+
+                osgUtil::IntersectVisitor iv;
+                iv.addLineSegment(lineSegment.get());
+
+                _rootnode->accept(iv);
+
+                if (iv.hits())
+                {
+                
+                    osgUtil::IntersectVisitor::HitList& hitList = iv.getHitList(lineSegment.get());
+                    if (!hitList.empty())
+                    {
+                    
+                        osgUtil::Hit& hit = hitList.front();
+                        addPoint(hit.getWorldIntersectPoint());
+                    }
+
+                }
+
+                return true;
+            }
+            else if (ea.getKey()=='e')
+            {
+                endOccluder();
+                return true;
+            }
+            else if (ea.getKey()=='O')
+            {
+                if (_occluders.valid())
+                {
+                    std::cout<<"saving occluders to 'saved_occluders.osg'"<<std::endl;
+                    osgDB::writeNodeFile(*_occluders,"saved_occluders.osg");
+                }
+                else
+                {
+                    std::cout<<"no occluders to save"<<std::endl;
+                }
+                return true;
+            }
+            return false;
+        }
+
+        default:
+            return false;
+    }
+}
+
+void OccluderEventHandler::addPoint(const osg::Vec3& pos)
+{
+    std::cout<<"add point "<<pos<<std::endl;
+    
+    if (!_convexPlanerOccluder.valid()) _convexPlanerOccluder = new osg::ConvexPlanerOccluder;
+    
+    osg::ConvexPlanerPolygon& occluder = _convexPlanerOccluder->getOccluder();
+    occluder.add(pos);
+    
+}
+                
+void OccluderEventHandler::endOccluder()
+{
+    if (_convexPlanerOccluder.valid()) 
+    {
+        if (_convexPlanerOccluder->getOccluder().getVertexList().size()>=3)
+        {
+            osg::OccluderNode* occluderNode = osgNew osg::OccluderNode;
+            occluderNode->setOccluder(_convexPlanerOccluder.get());
+
+            if (!_occluders.valid())
+            {
+                _occluders = new osg::Group;
+                _rootnode->addChild(_occluders.get());
+            }
+            _occluders->addChild(occluderNode);
+
+            std::cout<<"created occluder"<<std::endl;
+        }
+        else
+        {
+            std::cout<<"Occluder requires at least 3 points to create occluder."<<std::endl;
+        }
+    }
+    else
+    {
+        std::cout<<"No occluder points to create occluder with."<<std::endl;
+    }
+    
+    // reset current occluder.
+    _convexPlanerOccluder = NULL;
+}
+
+
 osg::Node* createOccluder(const osg::Vec3& v1,const osg::Vec3& v2,const osg::Vec3& v3,const osg::Vec3& v4,float holeRatio=-1.0f)
 {
    // create and occluder which will site along side the loadmodel model.
@@ -125,7 +271,7 @@ osg::Node* createOccluder(const osg::Vec3& v1,const osg::Vec3& v2,const osg::Vec
  
  }
 
-osg::Node* createOccludersAroundModel(osg::Node* model)
+osg::Group* createOccludersAroundModel(osg::Node* model)
 {
     osg::Group* scene = osgNew osg::Group;
     scene->setName("rootgroup");
@@ -187,6 +333,14 @@ int main( int argc, char **argv )
     std::vector<std::string> commandLine;
     for(int i=1;i<argc;++i) commandLine.push_back(argv[i]);
     
+    bool manuallyCreateImpostors = false;
+
+    std::vector<std::string>::iterator itr=std::find(commandLine.begin(),commandLine.end(),std::string("-c"));
+    if (itr!=commandLine.end())    
+    {
+        manuallyCreateImpostors = true;
+        commandLine.erase(itr);
+    }
 
     // initialize the viewer.
     osgGLUT::Viewer viewer;
@@ -208,12 +362,23 @@ int main( int argc, char **argv )
         return 1;
     }
     
-    // add the occluders to the loaded model.
-    osg::Node* rootnode = createOccludersAroundModel(loadedmodel);
-    
     // run optimization over the scene graph
     osgUtil::Optimizer optimzer;
-    optimzer.optimize(rootnode);
+    optimzer.optimize(loadedmodel);
+
+    // add the occluders to the loaded model.
+    osg::Group* rootnode = NULL;
+    
+    if (manuallyCreateImpostors)
+    {
+        rootnode = new osg::Group;
+        rootnode->addChild(loadedmodel);
+    }
+    else    
+    {
+        rootnode = createOccludersAroundModel(loadedmodel);
+    }
+    
      
     // add a viewport to the viewer and attach the scene graph.
     viewer.addViewport( rootnode );
@@ -223,6 +388,11 @@ int main( int argc, char **argv )
     viewer.registerCameraManipulator(new osgGA::FlightManipulator);
     viewer.registerCameraManipulator(new osgGA::DriveManipulator);
 
+    if (manuallyCreateImpostors)
+    {
+        viewer.setEventHandler(new OccluderEventHandler(viewer.getViewportSceneView(0),rootnode));
+    }
+
     // open the viewer window.
     viewer.open();
     
diff --git a/src/osgGA/KeySwitchCameraManipulator.cpp b/src/osgGA/KeySwitchCameraManipulator.cpp
index 315a2a829..9f87189cc 100644
--- a/src/osgGA/KeySwitchCameraManipulator.cpp
+++ b/src/osgGA/KeySwitchCameraManipulator.cpp
@@ -13,6 +13,13 @@ void KeySwitchCameraManipulator::addCameraManipulator(int key, std::string name,
     }
 }
 
+void KeySwitchCameraManipulator::addNumberedCameraManipulator(CameraManipulator *cm)
+{
+    if(!cm) return;
+    addCameraManipulator('1'+_manips.size(),"camera",cm);
+}
+
+
 bool KeySwitchCameraManipulator::handle(const GUIEventAdapter& ea,GUIActionAdapter& aa)
 {
     if(ea.getEventType()==GUIEventAdapter::KEYBOARD){
diff --git a/src/osgGLUT/Viewer.cpp b/src/osgGLUT/Viewer.cpp
index b02d638fd..71f10eea7 100644
--- a/src/osgGLUT/Viewer.cpp
+++ b/src/osgGLUT/Viewer.cpp
@@ -290,6 +290,11 @@ unsigned int Viewer::registerCameraManipulator(osgGA::CameraManipulator* cm,
     return pos;
 }
 
+void Viewer::setEventHandler(osgGA::GUIEventHandler* handler,unsigned int viewport = 0)
+{
+    ViewportDef &viewp = _viewportList[viewport];
+    viewp._eventHandler = handler;
+}
 
 void Viewer::setFocusedViewport(unsigned int pos)
 {
@@ -337,11 +342,16 @@ float Viewer::app(unsigned int viewport)
     osg::ref_ptr<GLUTEventAdapter> ea = osgNew GLUTEventAdapter;
     ea->adaptFrame(_frameStamp->getReferenceTime());
 
-    if (_viewportList[viewport]._cameraManipulator->handle(*ea,*this))
+    if (_viewportList[viewport]._eventHandler.valid() && _viewportList[viewport]._eventHandler->handle(*ea,*this))
+    {
+        // event handler handle this call.
+    }
+    else if (_viewportList[viewport]._cameraManipulator->handle(*ea,*this))
     {
         //        osg::notify(osg::INFO) << "Handled update frame"<< std::endl;
     }
 
+
     // do app traversal.
     
     getViewportSceneView(viewport)->setFrameStamp(_frameStamp.get());
@@ -704,6 +714,11 @@ void Viewer::reshape(GLint w, GLint h)
         {
             //        osg::notify(osg::INFO) << "Handled reshape "<< std::endl;
         }
+        if (itr->_eventHandler.valid() && itr->_eventHandler->handle(*ea,*this))
+        {
+            // event handler handle this call.
+        }
+    
     }
 }
 
@@ -713,7 +728,11 @@ void Viewer::mouseMotion(int x, int y)
     osg::ref_ptr<GLUTEventAdapter> ea = osgNew GLUTEventAdapter;
     ea->adaptMouseMotion(clockSeconds(),x,y);
 
-    if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this))
+    if (_viewportList[_focusedViewport]._eventHandler.valid() && _viewportList[_focusedViewport]._eventHandler->handle(*ea,*this))
+    {
+        // event handler handle this call.
+    }
+    else if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this))
     {
         //        osg::notify(osg::INFO) << "Handled mouseMotion "<<ea->_buttonMask<<" x="<<ea->_mx<<" y="<<ea->_my<< std::endl;
     }
@@ -737,7 +756,11 @@ void Viewer::mousePassiveMotion(int x, int y)
           setFocusedViewport(focus);
     }
 
-    if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this))
+    if (_viewportList[_focusedViewport]._eventHandler.valid() && _viewportList[_focusedViewport]._eventHandler->handle(*ea,*this))
+    {
+        // event handler handle this call.
+    }
+    else if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this))
     {
         //        osg::notify(osg::INFO) << "Handled mousePassiveMotion "<<ea->_buttonMask<<" x="<<ea->_mx<<" y="<<ea->_my<< std::endl;
     }
@@ -761,7 +784,11 @@ void Viewer::mouse(int button, int state, int x, int y)
           setFocusedViewport(focus);
     }
 
-    if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this))
+    if (_viewportList[_focusedViewport]._eventHandler.valid() && _viewportList[_focusedViewport]._eventHandler->handle(*ea,*this))
+    {
+        // event handler handle this call.
+    }
+    else if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this))
     {
         //        osg::notify(osg::INFO) << "Handled mouse "<<ea->_buttonMask<<" x="<<ea->_mx<<" y="<<ea->_my<< std::endl;
     }
@@ -775,8 +802,14 @@ void Viewer::keyboard(unsigned char key, int x, int y)
     osg::ref_ptr<GLUTEventAdapter> ea = osgNew GLUTEventAdapter;
     ea->adaptKeyboard(clockSeconds(),key,x,y);
 
-    if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this)) 
-      return;
+    if (_viewportList[_focusedViewport]._eventHandler.valid() && _viewportList[_focusedViewport]._eventHandler->handle(*ea,*this))
+    {
+        return;
+    }
+    else if (_viewportList[_focusedViewport]._cameraManipulator->handle(*ea,*this))
+    {
+        return;
+    }
 
 
 
diff --git a/src/osgUtil/Optimizer.cpp b/src/osgUtil/Optimizer.cpp
index 3b2425dc5..a3a1dd68e 100644
--- a/src/osgUtil/Optimizer.cpp
+++ b/src/osgUtil/Optimizer.cpp
@@ -7,6 +7,7 @@
 #include <osg/Geometry>
 #include <osg/GeoSet>
 #include <osg/Notify>
+#include <osg/OccluderNode>
 
 #include <typeinfo>
 #include <algorithm>
@@ -72,9 +73,11 @@ void Optimizer::optimize(osg::Node* node, unsigned int options)
     if (options & SHARE_DUPLICATE_STATE)
     {
     #if (defined(_MSC_VER) && _MSC_VER<1300 && !defined(_STLPORT_VERSION))
-        osg::notify(osg::NOTICE)<<"Warning: VisualStudio 6.0 native STL build, unable to run state optimizer due to bugs in its STL."<<std::endl; 
-        osg::notify(osg::NOTICE)<<"         This may impare performance significantly for larger models.  It is recommend that one "<<std::endl; 
-        osg::notify(osg::NOTICE)<<"         compiles against STLport or use Visual Studio .NET compiler which also fix these VS 6.0 STL bugs "<<std::endl; 
+        osg::notify(osg::NOTICE)<<"Warning: this application was built with VisualStudio 6.0's native STL,"<<std::endl;
+        osg::notify(osg::NOTICE)<<"         and due to bugs in VS's STL we are unable to run state optimizer."<<std::endl; 
+        osg::notify(osg::NOTICE)<<"         This may impare performance significantly for larger models."<<std::endl; 
+        osg::notify(osg::NOTICE)<<"         It is recommend that one compiles against STLport or use "<<std::endl; 
+        osg::notify(osg::NOTICE)<<"         Visual Studio .NET compiler which also fix these VS 6.0 STL bugs "<<std::endl; 
     #else
         StateVisitor osv;
         node->accept(osv);
@@ -931,7 +934,8 @@ void Optimizer::RemoveEmptyNodesVisitor::apply(osg::Group& group)
 {
     if (group.getNumParents()>0)
     {
-        if (group.getNumChildren()==0)
+        // only remove empty groups, but not empty occluders.
+        if (group.getNumChildren()==0 && !dynamic_cast<osg::OccluderNode*>(&group))
         {
             _redundentNodeList.insert(&group);
         }