From Farshid Lashkari, "I noticed that osg::notify does not output to stderr when using either FATAL or WARN severity levels. There is code in osg::StandardNotifyHandler::notify that will use stderr based on the severity level, but it is disabled by an #if 0. I'm assuming this was a mistake and have re-enabled the code.
Many IDEs will capture the output of processes and highlight stderr messages in red. After upgrading from OSG 1.2, I was noticing that none of the error messages were being highlighted, which I find quite useful."