From Mathias Froehlich, "I have extended the X11 pbuffer code to use either the complete set of glx 1.3

pbuffer functions or exactly ask for the extensions we need to call the
apropriate glx extension functions for and around pbuffers extensions.
The glx 1.3 version of this functios are prefered. If this is not pressent we
are looking for the glx extensions and check for them.
Prevously we just used some mix of the glx 1.3 functions or the extension
functions without making sure that this extension is present.
"

include/osg/GLExtensions

@@ -28,6 +28,10 @@ namespace osg {
 */
 extern OSG_EXPORT float getGLVersionNumber();
 
+/** Return true if "extension" is contained in "extensionString".
+*/
+extern OSG_EXPORT bool isExtensionInExtensionString(const char *extension, const char *extensionString);
+
 /** Return true if OpenGL "extension" is supported.
   * Note: Must only be called within a valid OpenGL context,
   * undefined behavior may occur otherwise.

include/osgViewer/api/X11/PixelBufferX11

@@ -77,7 +77,6 @@ class OSGVIEWER_EXPORT PixelBufferX11 : public osg::GraphicsContext
 
         Display* getDisplay() const { return _display; }
         
-        Window& getParent() { return _parent; }
         GLXPbuffer& getPbuffer() { return _pbuffer; }
         GLXContext& getGLXContext() { return _glxContext; }
 
@@ -91,13 +90,14 @@ class OSGVIEWER_EXPORT PixelBufferX11 : public osg::GraphicsContext
 
         bool            _valid;
         Display*        _display;
-        Window          _parent;
         GLXPbuffer      _pbuffer;
         XVisualInfo*    _visualInfo;
         GLXContext      _glxContext;
 
         bool            _initialized;
         bool            _realized;
+
+        bool            _useGLX1_3;
 };
 
 }