OBApplication sits in libob.framework.a. It's in gg:ppc-morphos/lib in the SDK. Sorry, I forgot to update the Frameworks/Examples/Makefile. Just edit -lob_debug.framework -lmui_debug.framework to -lob.framework -lmui.framework respectively.

Did you check if the Flow Studio project compiles OK? That's the CustomClass2.xprj file - open that from the Project menu in Flow.