This is very similar to the approach I want to take with 'command-line construction' (Brad will recall many e-mails sent in my attempt to describe my approach): http://www.cnb.uam.es/~bioinfo/Colimate/Extra_Docs/ You can see from the screenshots that command-line options are translated into GUI widgets. The major difference between Colimate and my own plans for vsh/Loci command-line construction, is that the definition of command-line options (or the construction of the interface) is done by connecting nodes. Jeff