Moin Moin,
i'm usung the Ruby Graph Library (rgl.sourceforge.net) to scan function 
libraries. If function A is used in function B, i add an edge to the 
Graph from B to A.
To indicate, that a function isn't used in any other function, i would 
just like to add a single knode without any edge.
I tried 'add_vertex' but no vertices are shown by dotty.

Anybody, who can enlight me ?

Thanks
ralf