From Robert Osfield and Richard Schmidt, made fixes inspired by an original submission from Richard which

highlighted problems with Light, ClipPlane and Hint usage in osg::State's usage of cloneType
and reassignment of target/num in StateSet/these StateAttributes.

src/osg/Hint.cpp

@@ -12,6 +12,7 @@
 */
 
 #include <osg/Hint>
+#include <osg/StateSet>
 
 using namespace osg;
 
@@ -21,3 +22,45 @@ void Hint::apply(State& state) const
     
     glHint(_target, _mode);
 }
+
+void Hint::setTarget(GLenum target)
+{ 
+    if (_target==target) return;
+
+    if (_parents.empty())
+    {
+        _target = target;
+        return;
+    }
+
+    // take a reference to this clip plane to prevent it from going out of scope
+    // when we remove it temporarily from its parents.
+    osg::ref_ptr<Hint> hintRef = this;
+
+    // copy the parents as they _parents list will be changed by the subsequent removeAttributes.
+    ParentList parents = _parents;
+
+    // remove this attribute from its parents as its position is being changed
+    // and would no longer be valid.
+    ParentList::iterator itr;
+    for(itr = parents.begin();
+        itr != parents.end();
+        ++itr)
+    {
+        osg::StateSet* stateset = *itr;
+        stateset->removeAttribute(this);
+    }
+    
+    // assign the hint target
+    _target = target;
+
+    // add this attribute back into its original parents with its new position
+    for(itr = parents.begin();
+        itr != parents.end();
+        ++itr)
+    {
+        osg::StateSet* stateset = *itr;
+        stateset->setAttribute(this);
+    }
+}
+