I tried to check out the sources via anonynous cvs.
The server answered:
$ cvs -z3 -d:pserver:anonymous@cvs.wf-gdk.sourceforge.net:/cvsroot/wf-gdk co wfsource
Fatal error, aborting.
anoncvs_wf_gdk: no such user
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
cvs [checkout aborted]: authorization failed: server cvs.wf-gdk.sourceforge.net rejected access
so it seems that it's not set up completetly.