diff --git a/include/osgGL2/ProgramObject b/include/osgGL2/ProgramObject
index 10911126b..ffc3c69a8 100644
--- a/include/osgGL2/ProgramObject
+++ b/include/osgGL2/ProgramObject
@@ -68,18 +68,7 @@ class OSGGL2_EXPORT ProgramObject : public osg::StateAttribute
         META_StateAttribute(osgGL2, ProgramObject, PROGRAMOBJECT);
 
         /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
-        virtual int compare(const osg::StateAttribute& sa) const
-        {
-            // check the types are equal and then create the rhs variable
-            // used by the COMPARE_StateAttribute_Paramter macro's below.
-            COMPARE_StateAttribute_Types(ProgramObject,sa)
-
-            // compare each parameter in turn against the rhs.
-            COMPARE_StateAttribute_Parameter(_shaderObjectList);
-            // COMPARE_StateAttribute_Parameter(_pcpoList);
-
-            return 0; // passed all the above comparison macro's, must be equal.
-        }
+        virtual int compare(const osg::StateAttribute& sa) const;
 
 	/** If enabled, install our shader program in the GL pipeline,
 	  * performing any shader program rebuild operations that might
@@ -182,7 +171,9 @@ class OSGGL2_EXPORT ProgramObject : public osg::StateAttribute
 
     protected:	/*data*/
 	bool _enabled;
-	std::vector< ShaderObjectPtr > _shaderObjectList;
+        
+        typedef std::vector< ShaderObjectPtr > ShaderObjectList;
+	ShaderObjectList _shaderObjectList;
         mutable osg::buffered_value< osg::ref_ptr<PerContextProgObj> > _pcpoList;
 	mutable int _frameNumberOfLastPCPOUpdate;
 	mutable UniformValueList _univalList;
@@ -219,6 +210,8 @@ class OSGGL2_EXPORT ShaderObject : public osg::Object
         ShaderObject(const ShaderObject& rhs, const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY);
         META_Object(osgGL2, ShaderObject);
 
+        int compare(const ShaderObject& sa) const;
+
         // data access methods.
 
 	/** Load the ShaderObject's source code text from a string. */
diff --git a/include/osgGL2/UniformValue b/include/osgGL2/UniformValue
index 11632eee4..29b1ecb10 100644
--- a/include/osgGL2/UniformValue
+++ b/include/osgGL2/UniformValue
@@ -48,6 +48,8 @@ class UniformValue : public osg::Referenced
     public:
 	virtual void apply( Extensions *ext, const GLhandleARB progObj ) const = 0;
 
+        virtual int compare(const UniformValue& uv) const;
+
     protected:
 	UniformValue( const char* uniformName ) : _name( uniformName ) {};
 	virtual ~UniformValue() {};
@@ -73,8 +75,27 @@ class UniformValueTemplate: public UniformValue
     public:
 	UniformValueTemplate( const char* uniformName, T value ) :
 		UniformValue( uniformName ), _value( value ) {}
+
 	virtual void apply( Extensions *ext, const GLhandleARB progObj ) const;
 
+        virtual int compare(const UniformValue& uv) const 
+        {
+            if (this==&uv) return 0;
+            const std::type_info* type_lhs = &typeid(*this);
+            const std::type_info* type_rhs = &typeid(uv);
+            if (type_lhs->before(*type_rhs)) return -1;
+            if (*type_lhs != *type_rhs) return 1;
+            const UniformValueTemplate& rhs = static_cast<const UniformValueTemplate&>(uv);
+
+            if (_name<rhs._name) return -1;
+            if (rhs._name<_name) return 1;
+
+            if (_value<rhs._value) return -1;
+            if (rhs._value<_value) return 1;
+
+            return 0;
+        }
+
     protected:
 	UniformValueTemplate();
 	const T _value;
diff --git a/src/osgGL2/ProgramObject.cpp b/src/osgGL2/ProgramObject.cpp
index 129c5d412..2eef6dbdf 100644
--- a/src/osgGL2/ProgramObject.cpp
+++ b/src/osgGL2/ProgramObject.cpp
@@ -171,6 +171,42 @@ ProgramObject::~ProgramObject()
     }
 }
 
+int ProgramObject::compare(const osg::StateAttribute& sa) const
+{
+    // check the types are equal and then create the rhs variable
+    // used by the COMPARE_StateAttribute_Paramter macro's below.
+    COMPARE_StateAttribute_Types(ProgramObject,sa)
+    
+    if (_shaderObjectList.size()<rhs._shaderObjectList.size()) return -1;
+    if (_shaderObjectList.size()>rhs._shaderObjectList.size()) return 1;
+    
+    ShaderObjectList::const_iterator litr=_shaderObjectList.begin();
+    ShaderObjectList::const_iterator ritr=rhs._shaderObjectList.begin();
+    for(;
+        litr!=_shaderObjectList.end();
+        ++litr,++ritr)
+    {
+        int result = (*litr)->compare(*(*ritr));
+        if (result!=0) return result;
+    }
+    
+
+    if (_univalList.size()<rhs._univalList.size()) return -1;
+    if (_univalList.size()>rhs._univalList.size()) return 1;
+
+    UniformValueList::const_iterator luitr=_univalList.begin();
+    UniformValueList::const_iterator ruitr=rhs._univalList.begin();
+    for(;
+        luitr!=_univalList.end();
+        ++luitr,++ruitr)
+    {
+        int result = (*luitr)->compare(*(*ruitr));
+        if (result!=0) return result;
+    }
+
+    return 0; // passed all the above comparison macro's, must be equal.
+}
+
 
 // mark all PCPOs as needing a relink
 void ProgramObject::dirtyProgramObject()
@@ -415,6 +451,13 @@ ShaderObject::~ShaderObject()
     /*TODO*/
 }
 
+int ShaderObject::compare(const ShaderObject& so) const
+{
+    if (getShaderSource()<so.getShaderSource()) return -1;
+    if (so.getShaderSource()<getShaderSource()) return 1;
+    return 0;
+}
+
 // mark each PCSO (per-context Shader Object) as needing a recompile
 void ShaderObject::dirtyShaderObject()
 {
diff --git a/src/osgGL2/UniformValue.cpp b/src/osgGL2/UniformValue.cpp
index ef72c6da0..7e173f840 100644
--- a/src/osgGL2/UniformValue.cpp
+++ b/src/osgGL2/UniformValue.cpp
@@ -25,6 +25,13 @@
 using namespace osgGL2;
 using namespace osg;
 
+int UniformValue::compare(const UniformValue& uv) const
+{
+    if (_name<uv._name) return -1;
+    if (uv._name<_name) return 1;
+    return 0;
+}
+
 int UniformValue::getLocation( Extensions *ext, const GLhandleARB progObj ) const
 {
     GLint loc = ext->glGetUniformLocation( progObj, _name.c_str() );