refactored the getWindows(..) and getContexts(..) methods so that they produce

consistent ordering based on the order Camera/slave camera ordering.

src/osgViewer/ViewerBase.cpp

@@ -501,6 +501,22 @@ void ViewerBase::startThreading()
     osg::notify(osg::INFO)<<"Set up threading"<<std::endl;
 }
 
+void ViewerBase::getWindows(Windows& windows, bool onlyValid)
+{
+    windows.clear();
+
+    Contexts contexts;
+    getContexts(contexts, onlyValid);
+    
+    for(Contexts::iterator itr = contexts.begin();
+        itr != contexts.end();
+        ++itr)
+    {
+        osgViewer::GraphicsWindow* gw = dynamic_cast<osgViewer::GraphicsWindow*>(*itr);
+        if (gw) windows.push_back(gw);
+    }
+}
+
 void ViewerBase::checkWindowStatus()
 {
     Contexts contexts;