Added support for assigning GraphicsContext to individual GUIEventAdapter events,

and use of this within osgViewer::View to better track the sources of events.

src/osgGA/GUIEventAdapter.cpp

@@ -32,12 +32,12 @@ GUIEventAdapter::GUIEventAdapter():
     _windowHeight(1024),
     _key(0),
     _button(0),
-    _Xmin(0.0),
+    _Xmin(-1.0),
     _Xmax(1.0),
-    _Ymin(0.0),
+    _Ymin(-1.0),
     _Ymax(1.0),
-    _mx(0.5),
-    _my(0.5),
+    _mx(0.0),
+    _my(0.0),
     _pressure(0.0),
     _tiltX(0.0),
     _tiltY(0.0),
@@ -56,6 +56,7 @@ GUIEventAdapter::GUIEventAdapter(const GUIEventAdapter& rhs,const osg::CopyOp& c
     _handled(rhs._handled),
     _eventType(rhs._eventType),
     _time(rhs._time),
+    _context(rhs._context),
     _windowX(rhs._windowX),
     _windowY(rhs._windowY),
     _windowWidth(rhs._windowWidth),