diff --git a/include/osgViewer/api/Carbon/GraphicsWindowCarbon b/include/osgViewer/api/Carbon/GraphicsWindowCarbon
index 8b2c97ed3..092647ea7 100644
--- a/include/osgViewer/api/Carbon/GraphicsWindowCarbon
+++ b/include/osgViewer/api/Carbon/GraphicsWindowCarbon
@@ -121,6 +121,12 @@ class GraphicsWindowCarbon : public osgViewer::GraphicsWindow
         
         /// install the standard os-eventhandler
         void installEventHandler();
+        
+        /// get the AGL context
+        AGLContext getAGLContext() { return _context; }
+        
+        // get the pixelformat
+        AGLPixelFormat getAGLPixelFormat() { return _pixelFormat; }
 
     protected:
     
@@ -128,7 +134,7 @@ class GraphicsWindowCarbon : public osgViewer::GraphicsWindow
         
         void transformMouseXY(float& x, float& y);
         
-        AGLContext& getAGLContext() { return _context; }
+        
         
 
 
diff --git a/src/osgViewer/GraphicsWindowCarbon.cpp b/src/osgViewer/GraphicsWindowCarbon.cpp
index e44a7c9ef..c7891d5fd 100644
--- a/src/osgViewer/GraphicsWindowCarbon.cpp
+++ b/src/osgViewer/GraphicsWindowCarbon.cpp
@@ -475,7 +475,12 @@ struct OSXCarbonWindowingSystemInterface : public osg::GraphicsContext::Windowin
     
     /** @return a CGDirectDisplayID for a ScreenIdentifier */
     inline CGDirectDisplayID getDisplayID(const osg::GraphicsContext::ScreenIdentifier& si) {
-        return _displayIds[si.screenNum];
+        if (si.screenNum < _displayCount)
+            return _displayIds[si.screenNum];
+        else {
+            osg::notify(osg::WARN) << "GraphicsWindowCarbon :: invalid screen # " << si.screenNum << ", returning main-screen instead" << std::endl;
+            return _displayIds[0];
+        }
     }
 
     /** @return count of attached screens */