diff --git a/applications/osgviewer/osgviewer.cpp b/applications/osgviewer/osgviewer.cpp
index d94a0f5fe..b0dd33805 100644
--- a/applications/osgviewer/osgviewer.cpp
+++ b/applications/osgviewer/osgviewer.cpp
@@ -30,6 +30,106 @@
 
 #include <iostream>
 
+#include <osg/GLExtensions>
+
+#ifndef GL_ARB_sync
+#define GL_MAX_SERVER_WAIT_TIMEOUT        0x9111
+#define GL_OBJECT_TYPE                    0x9112
+#define GL_SYNC_CONDITION                 0x9113
+#define GL_SYNC_STATUS                    0x9114
+#define GL_SYNC_FLAGS                     0x9115
+#define GL_SYNC_FENCE                     0x9116
+#define GL_SYNC_GPU_COMMANDS_COMPLETE     0x9117
+#define GL_UNSIGNALED                     0x9118
+#define GL_SIGNALED                       0x9119
+#define GL_ALREADY_SIGNALED               0x911A
+#define GL_TIMEOUT_EXPIRED                0x911B
+#define GL_CONDITION_SATISFIED            0x911C
+#define GL_WAIT_FAILED                    0x911D
+#define GL_SYNC_FLUSH_COMMANDS_BIT        0x00000001
+#define GL_TIMEOUT_IGNORED                0xFFFFFFFFFFFFFFFFull
+#endif
+
+class MySwapBuffersCallback : public osg::GraphicsContext::SwapCallback
+{
+public:
+    MySwapBuffersCallback():
+        _extensionInitialized(false),
+        _glFenceSync(0),
+        _glIsSync(0),
+        _glDeleteSync(0),
+        _glClientWaitSync(0),
+        _glWaitSync(0),
+        _glGetInteger64v(0),
+        _glGetSynciv(0),
+        _previousSync(0)
+    {
+         OSG_NOTICE<<"Created Swap callback."<<std::endl;
+    }
+
+    void setUpExtensions()
+    {
+        _extensionInitialized = true;
+        osg::setGLExtensionFuncPtr(_glFenceSync, "glFenceSync");
+        osg::setGLExtensionFuncPtr(_glIsSync, "glIsSync");
+        osg::setGLExtensionFuncPtr(_glDeleteSync, "glDeleteSync");
+        osg::setGLExtensionFuncPtr(_glClientWaitSync, "glClientWaitSync");
+        osg::setGLExtensionFuncPtr(_glWaitSync, "glWaitSync");
+        osg::setGLExtensionFuncPtr(_glGetInteger64v, "glGetInteger64v");
+        osg::setGLExtensionFuncPtr(_glGetSynciv, "glGetSynciv");
+    }
+
+    virtual void swapBuffersImplementation(osg::GraphicsContext* gc)
+    {
+        // OSG_NOTICE<<"Before swap - place to do swap ready sync"<<std::endl;
+        gc->swapBuffersImplementation();
+        //glFinish();
+
+        if (!_extensionInitialized) setUpExtensions();
+
+        if (_glClientWaitSync)
+        {        
+            if (_previousSync)
+            {
+                unsigned int num_seconds = 1;
+                GLuint64 timeout = num_seconds * ((GLuint64)1000 * 1000 * 1000);
+                _glClientWaitSync(_previousSync, 0, timeout);
+
+                _glDeleteSync(_previousSync);
+            }
+
+            _previousSync = _glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
+        }
+        //gc->getState()->checkGLErrors("after glWaitSync");
+
+        //OSG_NOTICE<<"After swap"<<std::endl;
+    }
+
+    typedef int64_t GLint64;
+    typedef uint64_t GLuint64;
+    typedef struct __GLsync *GLsync;
+
+    typedef GLsync (GL_APIENTRY * PFNGLFENCESYNCPROC) (GLenum condition, GLbitfield flags);
+    typedef GLboolean (GL_APIENTRY * PFNGLISSYNCPROC) (GLsync sync);
+    typedef void (GL_APIENTRY * PFNGLDELETESYNCPROC) (GLsync sync);
+    typedef GLenum (GL_APIENTRY * PFNGLCLIENTWAITSYNCPROC) (GLsync sync, GLbitfield flags, GLuint64 timeout);
+    typedef void (GL_APIENTRY * PFNGLWAITSYNCPROC) (GLsync sync, GLbitfield flags, GLuint64 timeout);
+    typedef void (GL_APIENTRY * PFNGLGETINTEGER64VPROC) (GLenum pname, GLint64 *params);
+    typedef void (GL_APIENTRY * PFNGLGETSYNCIVPROC) (GLsync sync, GLenum pname, GLsizei bufSize, GLsizei *length, GLint *values);
+
+    bool                        _extensionInitialized;
+    
+    PFNGLFENCESYNCPROC          _glFenceSync;
+    PFNGLISSYNCPROC             _glIsSync;
+    PFNGLDELETESYNCPROC         _glDeleteSync;
+    PFNGLCLIENTWAITSYNCPROC     _glClientWaitSync;
+    PFNGLWAITSYNCPROC           _glWaitSync;
+    PFNGLGETINTEGER64VPROC      _glGetInteger64v;
+    PFNGLGETSYNCIVPROC          _glGetSynciv;
+
+    GLsync _previousSync;
+};
+
 int main(int argc, char** argv)
 {
     // use an ArgumentParser object to manage the program arguments.
@@ -110,6 +210,8 @@ int main(int argc, char** argv)
         viewer.setCameraManipulator( keyswitchManipulator.get() );
     }
 
+    bool doArbSync = arguments.read("--sync");
+
     // add the state manipulator
     viewer.addEventHandler( new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()) );
 
@@ -161,6 +263,18 @@ int main(int argc, char** argv)
 
     viewer.realize();
 
+    if (doArbSync)
+    {
+        osgViewer::ViewerBase::Contexts contexts;
+        viewer.getContexts(contexts);
+        for(osgViewer::ViewerBase::Contexts::iterator itr = contexts.begin();
+            itr != contexts.end();
+            ++itr)
+        {
+            (*itr)->setSwapCallback(new MySwapBuffersCallback);
+        }
+    }
+
     return viewer.run();
 
 }
diff --git a/src/osgManipulator/Dragger.cpp b/src/osgManipulator/Dragger.cpp
index 9f6aa1238..b667ca599 100644
--- a/src/osgManipulator/Dragger.cpp
+++ b/src/osgManipulator/Dragger.cpp
@@ -275,6 +275,19 @@ void Dragger::addDraggerCallback(DraggerCallback* dc)
 
 void Dragger::removeDraggerCallback(DraggerCallback* dc)
 {
+    for(Dragger::DraggerCallbacks::iterator itr = _draggerCallbacks.begin();
+        itr != _draggerCallbacks.end();
+        )
+    {
+        if (dc==itr->get())
+        {
+            itr = _draggerCallbacks.erase(itr);
+        }
+        else
+        {
+            ++itr;
+        }
+    }
 }
 
 
@@ -390,6 +403,7 @@ bool Dragger::handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter&
                         }
                     }
                 }
+                break;
             }
             case osgGA::GUIEventAdapter::DRAG:
             case osgGA::GUIEventAdapter::RELEASE: