From Mourad Boufarguine, "I gave projects folders in VS a try, it works for applications, plugins and examples but not for the osg core libraries.

Attached OsgMacroUtils.cmake is a tiny fix for this. OpenThreads is addressed seperately."

src/OpenThreads/win32/CMakeLists.txt

@@ -25,7 +25,7 @@ ADD_LIBRARY(${LIB_NAME}
     ${OPENTHREADS_VERSIONINFO_RC}
 )
 
-
+SET_TARGET_PROPERTIES(${LIB_NAME} PROPERTIES FOLDER "OSG Core")
 IF(OPENTHREADS_SONAMES)
   SET_TARGET_PROPERTIES(${LIB_NAME} PROPERTIES VERSION ${OPENTHREADS_VERSION} SOVERSION ${OPENTHREADS_SOVERSION})
 ENDIF()