From Miha Ravselj, "Regarding previous submission it was only partial solution. After further testing I found similar bug also in ClearNode? serializer.
//GLbitfield mask = GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT;
This line was problematic since it produced incorrect result when let's say COLOR flag is serialized
it should be null as in Camera serializer or in a proposed BitFlagsSerializer?
This line of code caused that whenever only GL_COLOR_BUFFER_BIT bit was written and on value read GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT was restored instead of GL_COLOR_BUFFER_BIT only.
//GLbitfield mask = 0; //this resolves the issue same as in camera
Also same bit-wise comparison bug was also present in write method.
As you can see there are total 3 bit mask serializers in OSG and all 3 had bugs so I decided to add ADD_BITFLAGS_SERIALIZER and replace USER serializers in osg::Camera, osg::ClearNode? and osgText::TextBase?. I have made sure that bitflags serializer does not break backwards-compatibility since it uses same code as user serializer does in all 3 cases. (see tester.cpp on how compatibility test was performed)"