diff --git a/src/osgViewer/CompositeViewer.cpp b/src/osgViewer/CompositeViewer.cpp
index 5bb9eff22..85045e898 100644
--- a/src/osgViewer/CompositeViewer.cpp
+++ b/src/osgViewer/CompositeViewer.cpp
@@ -1120,6 +1120,10 @@ void CompositeViewer::eventTraversal()
             {
                 osgGA::GUIEventAdapter* event = (*itr)->asGUIEventAdapter();
                 if (!event) continue;
+
+                // ignore event if it's already been handled.
+                if (event->getHandled()) continue;
+
                 switch(event->getEventType())
                 {
                     case(osgGA::GUIEventAdapter::KEYUP):
diff --git a/src/osgViewer/Viewer.cpp b/src/osgViewer/Viewer.cpp
index 3ab9f63b0..613e21b9f 100644
--- a/src/osgViewer/Viewer.cpp
+++ b/src/osgViewer/Viewer.cpp
@@ -989,6 +989,10 @@ void Viewer::eventTraversal()
         {
             osgGA::GUIEventAdapter* event = (*itr)->asGUIEventAdapter();
             if (!event) continue;
+
+            // ignore event if it's already been handled.
+            if (event->getHandled()) continue;
+
             switch(event->getEventType())
             {
                 case(osgGA::GUIEventAdapter::KEYUP):