diff --git a/examples/osgviewerFOX/FOX_OSG.cpp b/examples/osgviewerFOX/FOX_OSG.cpp
index 039b988c7..c2c154d4f 100644
--- a/examples/osgviewerFOX/FOX_OSG.cpp
+++ b/examples/osgviewerFOX/FOX_OSG.cpp
@@ -48,7 +48,7 @@ void GraphicsWindowFOX::init()
 		setState( new osg::State );
 		getState()->setGraphicsContext(this);
 
-		if (_traits.valid() && _traits->sharedContext)
+		if (_traits.valid() && _traits->sharedContext.valid())
 		{
 			getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
 			incrementContextIDUsageCount( getState()->getContextID() );   
diff --git a/examples/osgviewerWX/osgviewerWX.cpp b/examples/osgviewerWX/osgviewerWX.cpp
index 6cf6ecd7e..c4a198a4d 100644
--- a/examples/osgviewerWX/osgviewerWX.cpp
+++ b/examples/osgviewerWX/osgviewerWX.cpp
@@ -299,7 +299,7 @@ void GraphicsWindowWX::init()
         setState( new osg::State );
         getState()->setGraphicsContext(this);
 
-        if (_traits.valid() && _traits->sharedContext)
+        if (_traits.valid() && _traits->sharedContext.valid())
         {
             getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
             incrementContextIDUsageCount( getState()->getContextID() );
diff --git a/include/osg/GraphicsContext b/include/osg/GraphicsContext
index d7adf6dba..cd30b2f40 100644
--- a/include/osg/GraphicsContext
+++ b/include/osg/GraphicsContext
@@ -128,7 +128,7 @@ class OSG_EXPORT GraphicsContext : public Object
             bool getContextVersion(unsigned int& major, unsigned int& minor) const;
 
             // shared context
-            GraphicsContext* sharedContext;
+            osg::observer_ptr<GraphicsContext> sharedContext;
 
             osg::ref_ptr<osg::Referenced> inheritedWindowData;
 
diff --git a/include/osgViewer/GraphicsWindow b/include/osgViewer/GraphicsWindow
index e8f04cc9f..6d1593e54 100644
--- a/include/osgViewer/GraphicsWindow
+++ b/include/osgViewer/GraphicsWindow
@@ -247,7 +247,7 @@ class GraphicsWindowEmbedded : public GraphicsWindow
                 setState( new osg::State );
                 getState()->setGraphicsContext(this);
 
-                if (_traits.valid() && _traits->sharedContext)
+                if (_traits.valid() && _traits->sharedContext.valid())
                 {
                     getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
                     incrementContextIDUsageCount( getState()->getContextID() );
diff --git a/include/osgViewer/api/Carbon/GraphicsWindowCarbon b/include/osgViewer/api/Carbon/GraphicsWindowCarbon
index 693e53476..cc138a44b 100644
--- a/include/osgViewer/api/Carbon/GraphicsWindowCarbon
+++ b/include/osgViewer/api/Carbon/GraphicsWindowCarbon
@@ -48,7 +48,7 @@ class GraphicsWindowCarbon : public osgViewer::GraphicsWindow, public osgViewer:
                 setState( new osg::State );
                 getState()->setGraphicsContext(this);
 
-                if (_traits.valid() && _traits->sharedContext)
+                if (_traits.valid() && _traits->sharedContext.valid())
                 {
                     getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
                     incrementContextIDUsageCount( getState()->getContextID() );   
diff --git a/include/osgViewer/api/Carbon/PixelBufferCarbon b/include/osgViewer/api/Carbon/PixelBufferCarbon
index 5880450fe..60c4f51ef 100644
--- a/include/osgViewer/api/Carbon/PixelBufferCarbon
+++ b/include/osgViewer/api/Carbon/PixelBufferCarbon
@@ -45,7 +45,7 @@ class OSGVIEWER_EXPORT PixelBufferCarbon : public osg::GraphicsContext, public o
                 setState( new osg::State );
                 getState()->setGraphicsContext(this);
 
-                if (_traits.valid() && _traits->sharedContext)
+                if (_traits.valid() && _traits->sharedContext.valid())
                 {
                     getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
                     incrementContextIDUsageCount( getState()->getContextID() );   
diff --git a/include/osgViewer/api/Cocoa/GraphicsWindowCocoa b/include/osgViewer/api/Cocoa/GraphicsWindowCocoa
index 800e569d7..62908780b 100644
--- a/include/osgViewer/api/Cocoa/GraphicsWindowCocoa
+++ b/include/osgViewer/api/Cocoa/GraphicsWindowCocoa
@@ -76,7 +76,7 @@ class GraphicsWindowCocoa : public osgViewer::GraphicsWindow, public osgViewer::
                 setState( new osg::State );
                 getState()->setGraphicsContext(this);
 
-                if (_traits.valid() && _traits->sharedContext)
+                if (_traits.valid() && _traits->sharedContext.valid())
                 {
                     getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
                     incrementContextIDUsageCount( getState()->getContextID() );   
diff --git a/include/osgViewer/api/Cocoa/PixelBufferCocoa b/include/osgViewer/api/Cocoa/PixelBufferCocoa
index 6a1a51731..e00c1135b 100644
--- a/include/osgViewer/api/Cocoa/PixelBufferCocoa
+++ b/include/osgViewer/api/Cocoa/PixelBufferCocoa
@@ -47,7 +47,7 @@ class OSGVIEWER_EXPORT PixelBufferCocoa : public osg::GraphicsContext, public os
                 setState( new osg::State );
                 getState()->setGraphicsContext(this);
 
-                if (_traits.valid() && _traits->sharedContext)
+                if (_traits.valid() && _traits->sharedContext.valid())
                 {
                     getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
                     incrementContextIDUsageCount( getState()->getContextID() );   
diff --git a/include/osgViewer/api/IOS/GraphicsWindowIOS b/include/osgViewer/api/IOS/GraphicsWindowIOS
index 5e7f2afc8..481bfd632 100644
--- a/include/osgViewer/api/IOS/GraphicsWindowIOS
+++ b/include/osgViewer/api/IOS/GraphicsWindowIOS
@@ -72,7 +72,7 @@ class GraphicsWindowIOS : public osgViewer::GraphicsWindow
                 setState( new osg::State );
                 getState()->setGraphicsContext(this);
 
-                if (_traits.valid() && _traits->sharedContext)
+                if (_traits.valid() && _traits->sharedContext.valid())
                 {
                     getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
                     incrementContextIDUsageCount( getState()->getContextID() );   
diff --git a/include/osgViewer/api/X11/GraphicsWindowX11 b/include/osgViewer/api/X11/GraphicsWindowX11
index 47593e361..1628b0998 100644
--- a/include/osgViewer/api/X11/GraphicsWindowX11
+++ b/include/osgViewer/api/X11/GraphicsWindowX11
@@ -59,7 +59,7 @@ class OSGVIEWER_EXPORT GraphicsWindowX11 : public osgViewer::GraphicsWindow, pub
                 setState( new osg::State );
                 getState()->setGraphicsContext(this);
 
-                if (_traits.valid() && _traits->sharedContext)
+                if (_traits.valid() && _traits->sharedContext.valid())
                 {
                     getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
                     incrementContextIDUsageCount( getState()->getContextID() );   
diff --git a/src/osgQt/GraphicsWindowQt.cpp b/src/osgQt/GraphicsWindowQt.cpp
index ecb4f8b08..df269187a 100644
--- a/src/osgQt/GraphicsWindowQt.cpp
+++ b/src/osgQt/GraphicsWindowQt.cpp
@@ -382,7 +382,7 @@ bool GraphicsWindowQt::init( QWidget* parent, const QGLWidget* shareWidget, Qt::
     {
         // shareWidget
         if ( !shareWidget ) {
-            GraphicsWindowQt* sharedContextQt = dynamic_cast<GraphicsWindowQt*>(_traits->sharedContext);
+            GraphicsWindowQt* sharedContextQt = dynamic_cast<GraphicsWindowQt*>(_traits->sharedContext.get());
             if ( sharedContextQt )
                 shareWidget = sharedContextQt->getGLWidget();
         }
@@ -422,7 +422,7 @@ bool GraphicsWindowQt::init( QWidget* parent, const QGLWidget* shareWidget, Qt::
     getState()->setGraphicsContext(this);
 
     // initialize contextID
-    if ( _traits.valid() && _traits->sharedContext )
+    if ( _traits.valid() && _traits->sharedContext.valid() )
     {
         getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
         incrementContextIDUsageCount( getState()->getContextID() );
diff --git a/src/osgViewer/GraphicsWindowCarbon.cpp b/src/osgViewer/GraphicsWindowCarbon.cpp
index 648c0bc75..5aa55ec2f 100644
--- a/src/osgViewer/GraphicsWindowCarbon.cpp
+++ b/src/osgViewer/GraphicsWindowCarbon.cpp
@@ -399,7 +399,7 @@ bool GraphicsWindowCarbon::realizeImplementation()
     // create the context
     AGLContext sharedContextCarbon = NULL;
 
-    GraphicsHandleCarbon* graphicsHandleCarbon = dynamic_cast<GraphicsHandleCarbon*>(_traits->sharedContext);
+    GraphicsHandleCarbon* graphicsHandleCarbon = dynamic_cast<GraphicsHandleCarbon*>(_traits->sharedContext.get());
     if (graphicsHandleCarbon)
     {
         sharedContextCarbon = graphicsHandleCarbon->getAGLContext();
diff --git a/src/osgViewer/GraphicsWindowCocoa.mm b/src/osgViewer/GraphicsWindowCocoa.mm
index 58c718a9d..598aa590e 100644
--- a/src/osgViewer/GraphicsWindowCocoa.mm
+++ b/src/osgViewer/GraphicsWindowCocoa.mm
@@ -1186,7 +1186,7 @@ bool GraphicsWindowCocoa::realizeImplementation()
     // create the context
     NSOpenGLContext* sharedContext = NULL;
 
-    GraphicsHandleCocoa* graphicsHandleCocoa = dynamic_cast<GraphicsHandleCocoa*>(_traits->sharedContext);
+    GraphicsHandleCocoa* graphicsHandleCocoa = dynamic_cast<GraphicsHandleCocoa*>(_traits->sharedContext.get());
     if (graphicsHandleCocoa)
     {
         sharedContext = graphicsHandleCocoa->getNSOpenGLContext();
diff --git a/src/osgViewer/GraphicsWindowWin32.cpp b/src/osgViewer/GraphicsWindowWin32.cpp
index 06650cc91..6aacaa0d4 100644
--- a/src/osgViewer/GraphicsWindowWin32.cpp
+++ b/src/osgViewer/GraphicsWindowWin32.cpp
@@ -1150,7 +1150,7 @@ GraphicsWindowWin32::GraphicsWindowWin32( osg::GraphicsContext::Traits* traits )
         setState( new osg::State );
         getState()->setGraphicsContext(this);
 
-        if (_traits.valid() && _traits->sharedContext)
+        if (_traits.valid() && _traits->sharedContext.valid())
         {
             getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
             incrementContextIDUsageCount( getState()->getContextID() );
@@ -1903,7 +1903,7 @@ bool GraphicsWindowWin32::realizeImplementation()
         if (!_initialized) return false;
     }
 
-    if (_traits.valid() && (_traits->sharedContext || _traits->vsync || _traits->swapGroupEnabled))
+    if (_traits.valid() && (_traits->sharedContext.valid() || _traits->vsync || _traits->swapGroupEnabled))
     {
         // make context current so we can test capabilities and set up context sharing
         struct RestoreContext
@@ -1932,7 +1932,7 @@ bool GraphicsWindowWin32::realizeImplementation()
         }
 
         // set up sharing of contexts if required
-        GraphicsHandleWin32* graphicsHandleWin32 = dynamic_cast<GraphicsHandleWin32*>(_traits->sharedContext);
+        GraphicsHandleWin32* graphicsHandleWin32 = dynamic_cast<GraphicsHandleWin32*>(_traits->sharedContext.get());
         if (graphicsHandleWin32)
         {
             if (!wglShareLists(graphicsHandleWin32->getWGLContext(), getWGLContext()))
diff --git a/src/osgViewer/GraphicsWindowX11.cpp b/src/osgViewer/GraphicsWindowX11.cpp
index d551f36e4..ba217f173 100644
--- a/src/osgViewer/GraphicsWindowX11.cpp
+++ b/src/osgViewer/GraphicsWindowX11.cpp
@@ -717,7 +717,7 @@ void GraphicsWindowX11::init()
     }
 
     // get any shared GLX contexts
-    GraphicsHandleX11* graphicsHandleX11 = dynamic_cast<GraphicsHandleX11*>(_traits->sharedContext);
+    GraphicsHandleX11* graphicsHandleX11 = dynamic_cast<GraphicsHandleX11*>(_traits->sharedContext.get());
     Context sharedContext = graphicsHandleX11 ? graphicsHandleX11->getContext() : 0;
 
     #ifdef OSG_USE_EGL
diff --git a/src/osgViewer/PixelBufferCarbon.cpp b/src/osgViewer/PixelBufferCarbon.cpp
index 61b674391..4f13d5406 100644
--- a/src/osgViewer/PixelBufferCarbon.cpp
+++ b/src/osgViewer/PixelBufferCarbon.cpp
@@ -81,7 +81,7 @@ bool PixelBufferCarbon::realizeImplementation()
     AGLContext sharedContext = NULL;
 
     // get any shared AGL contexts
-    GraphicsHandleCarbon* graphicsHandleCarbon = dynamic_cast<GraphicsHandleCarbon*>(_traits->sharedContext);
+    GraphicsHandleCarbon* graphicsHandleCarbon = dynamic_cast<GraphicsHandleCarbon*>(_traits->sharedContext.get());
     if (graphicsHandleCarbon)
     {
         sharedContext = graphicsHandleCarbon->getAGLContext();
diff --git a/src/osgViewer/PixelBufferCocoa.mm b/src/osgViewer/PixelBufferCocoa.mm
index ccff33be1..343840ff6 100644
--- a/src/osgViewer/PixelBufferCocoa.mm
+++ b/src/osgViewer/PixelBufferCocoa.mm
@@ -63,7 +63,7 @@ bool PixelBufferCocoa::realizeImplementation()
     // create the context
     NSOpenGLContext* sharedContext = NULL;
     
-    GraphicsHandleCocoa* graphicsHandleCocoa = dynamic_cast<GraphicsHandleCocoa*>(_traits->sharedContext);
+    GraphicsHandleCocoa* graphicsHandleCocoa = dynamic_cast<GraphicsHandleCocoa*>(_traits->sharedContext.get());
     if (graphicsHandleCocoa) 
     {
         sharedContext = graphicsHandleCocoa->getNSOpenGLContext();
diff --git a/src/osgViewer/PixelBufferWin32.cpp b/src/osgViewer/PixelBufferWin32.cpp
index a343bd1b2..0512a85eb 100644
--- a/src/osgViewer/PixelBufferWin32.cpp
+++ b/src/osgViewer/PixelBufferWin32.cpp
@@ -463,7 +463,7 @@ PixelBufferWin32::PixelBufferWin32( osg::GraphicsContext::Traits* traits ):
         setState( new osg::State );
         getState()->setGraphicsContext( this );
 
-        if (_traits.valid() && _traits->sharedContext )
+        if (_traits.valid() && _traits->sharedContext.valid() )
         {
             getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
             incrementContextIDUsageCount( getState()->getContextID() );
@@ -658,9 +658,9 @@ bool PixelBufferWin32::realizeImplementation()
 
     if (!_initialized) return false;
 
-    if ( _traits->sharedContext )
+    if ( _traits->sharedContext.valid() )
     {
-        GraphicsHandleWin32* graphicsHandleWin32 = dynamic_cast<GraphicsHandleWin32*>(_traits->sharedContext);
+        GraphicsHandleWin32* graphicsHandleWin32 = dynamic_cast<GraphicsHandleWin32*>(_traits->sharedContext.get());
         if (graphicsHandleWin32)
         {
             if ( !wglShareLists(graphicsHandleWin32->getWGLContext(), _hglrc) )
diff --git a/src/osgViewer/PixelBufferX11.cpp b/src/osgViewer/PixelBufferX11.cpp
index bec072c83..ea6e5b36d 100644
--- a/src/osgViewer/PixelBufferX11.cpp
+++ b/src/osgViewer/PixelBufferX11.cpp
@@ -43,7 +43,7 @@ PixelBufferX11::PixelBufferX11(osg::GraphicsContext::Traits* traits)
         setState( new osg::State );
         getState()->setGraphicsContext(this);
 
-        if (_traits.valid() && _traits->sharedContext)
+        if (_traits.valid() && _traits->sharedContext.valid())
         {
             getState()->setContextID( _traits->sharedContext->getState()->getContextID() );
             incrementContextIDUsageCount( getState()->getContextID() );
@@ -216,7 +216,7 @@ void PixelBufferX11::init()
     }
 
     // get any shared GLX contexts
-    GraphicsHandleX11* graphicsHandleX11 = dynamic_cast<GraphicsHandleX11*>(_traits->sharedContext);
+    GraphicsHandleX11* graphicsHandleX11 = dynamic_cast<GraphicsHandleX11*>(_traits->sharedContext.get());
     Context sharedContext = graphicsHandleX11 ? graphicsHandleX11->getContext() : 0;
 
     _context = glXCreateContext( _display, _visualInfo, sharedContext, True );