From Don Leich, "Here are a couple of fixes for the file examples/osgviewerQT/QOSGWidget.cpp to

address some OS X issues.  Most of these fixes were previously submitted by Julian Scheid.  However, this patch however should not break the example for non-OS X builds and has been tested on 64-bit Linux as well as Mac OS X 10.5.

o  The value returned by QWidget::winId() is not usable as input for
WindowData under OS X the way it is for both Windows and Unix.  Julian's fix
for this uses the Carbon API.  Since the fix for X11 in unknown, it is now
assumed that OSG has been built with OSG_WINDOWING_SYSTEM='Carbon' for this
example to work at all when running under OS X.

o  The CompositeViewer version would hang on exit with the original timer start
argument.  Changing the argument value to match the non-composite version
seemed to cure the hanging.

o  Julian's patch altered the setGeometry position to 30/30 in order to see any
window decorations.  I did not have this problem, but left his changes intact.

o  The non-composite viewer needed it's camera initialization defered until
after the ViewerQOSG's Qt base class had been initialized.  Otherwise, the view
did not cover the entire window.
"

examples/osgviewerQT/QOSGWidget.cpp

@@ -22,7 +22,6 @@
     #include <QtCore/QTimer>
     #include <QtGui/QKeyEvent>
     #include <QtGui/QApplication>
-    #include <QtOpenGL/QGLWidget>
     #include <QtGui/QtGui>
     #include <QtGui/QWidget>
     using Qt::WindowFlags;
@@ -50,7 +49,7 @@
 #include <osgViewer/api/Win32/GraphicsWindowWin32>
 typedef HWND WindowHandle;
 typedef osgViewer::GraphicsWindowWin32::WindowData WindowData;
-#elif defined(__APPLE__)
+#elif defined(__APPLE__)  // Assume using Carbon on Mac.
 #include <osgViewer/api/Carbon/GraphicsWindowCarbon>
 typedef WindowRef WindowHandle;
 typedef osgViewer::GraphicsWindowCarbon::WindowData WindowData;
@@ -146,12 +145,17 @@ void QOSGWidget::createContext()
     traits->sampleBuffers = ds->getMultiSamples();
     traits->samples = ds->getNumMultiSamples();
 
-#if defined(__APPLE__)
+#if defined(__APPLE__) 
+    // Extract a WindowPtr from the HIViewRef that QWidget::winId() returns.
+    // Without this change, the peer tries to call GetWindowPort on the HIViewRef
+    // which returns 0 and we only render white.
     traits->inheritedWindowData = new WindowData(HIViewGetWindow((HIViewRef)winId()));
-#else
+
+#else // all others
     traits->inheritedWindowData = new WindowData(winId());
 #endif
 
+
     if (ds->getStereo())
     {
         switch(ds->getStereoMode())
@@ -268,26 +272,25 @@ void QOSGWidget::mouseMoveEvent( QMouseEvent* event )
 
 
 
-
-
-
-
 class ViewerQOSG : public osgViewer::Viewer, public QOSGWidget
 {
     public:
 
         ViewerQOSG(QWidget * parent = 0, const char * name = 0, WindowFlags f = 0):
             QOSGWidget( parent, name, f )
+        {
+            setThreadingModel(osgViewer::Viewer::SingleThreaded);
+
+            connect(&_timer, SIGNAL(timeout()), this, SLOT(update()));
+            _timer.start(10);
+        }
+        
+        void updateCamera()
         {
             getCamera()->setViewport(new osg::Viewport(0,0,width(),height()));
             getCamera()->setProjectionMatrixAsPerspective(30.0f, static_cast<double>(width())/static_cast<double>(height()), 1.0f, 10000.0f);
             getCamera()->setGraphicsContext(getGraphicsWindow());
-
+        }
-            setThreadingModel(osgViewer::Viewer::SingleThreaded);
-
-        connect(&_timer, SIGNAL(timeout()), this, SLOT(update()));
-            _timer.start(10);
-    }
 
         virtual void paintEvent( QPaintEvent * event ) { frame(); }
 
@@ -308,7 +311,10 @@ class CompositeViewerQOSG : public osgViewer::CompositeViewer, public QOSGWidget
             setThreadingModel(osgViewer::CompositeViewer::SingleThreaded);
 
             connect(&_timer, SIGNAL(timeout()), this, SLOT(repaint()));
-            _timer.start(1);
+
+            // The app would hang on exit when using start(1).  Behaves better with 10
+            // like the non-composite viewer.  Was this just a typo?
+            _timer.start(10);
         }
 
         virtual void paintEvent( QPaintEvent * event ) { frame(); }
@@ -396,7 +402,11 @@ int mainQOSGWidget(QApplication& a, osg::ArgumentParser& arguments)
     if (arguments.read("--CompositeViewer"))
     {
         osg::ref_ptr<CompositeViewerQOSG> viewerWindow(new CompositeViewerQOSG);
+
         viewerWindow->setGeometry(0,0,640,480);
+        // Open the ViewerQOSG window at 30/30 instead of 0/0.  In some instances,
+        // the window may otherwise lack any window decoration.
+        // viewerWindow->setGeometry(30,30,640,480);
 
         unsigned int width = viewerWindow->width();
         unsigned int height = viewerWindow->height();
@@ -475,6 +485,7 @@ int mainQOSGWidget(QApplication& a, osg::ArgumentParser& arguments)
                 view->setCameraManipulator(new osgGA::TrackballManipulator);
                 view->setSceneData(loadedModel.get ());
                 ctimer->_viewer->addView(view);
+
             }
 
         //uiLayout->addWidget (ctimer);
@@ -495,8 +506,16 @@ int mainQOSGWidget(QApplication& a, osg::ArgumentParser& arguments)
     else
     {
         osg::ref_ptr<ViewerQOSG> viewerWindow(new ViewerQOSG);
-        viewerWindow->setGeometry(0,0,640,480);
 
+        // Open the ViewerQOSG window at 30/30 instead of 0/0.  In some instances,
+        // the window may otherwise lack any window decoration.
+        viewerWindow->setGeometry(0,0,640,480);
+        // viewerWindow->setGeometry(30,30,640,480);
+
+        // Setup the camera only after ViewerQOSG's Qt base class has been
+        // initialized. Without this change the view doesn't cover the whole
+        // window.
+        viewerWindow->updateCamera();
         viewerWindow->setCameraManipulator(new osgGA::TrackballManipulator);
         viewerWindow->setSceneData(loadedModel.get());