Just in case this was missed from my earlier note ... you don't *need* graphviz to use workflow. So if a user feels that somehow using graphviz makes OpenACS "not free" then all they need to do is to tell workflow not to use graphviz (by setting the path parameter to graphviz blank, IIRC). You can build and examine workflows interactively without graphviz, you just get a relatively ugly HTML diagram of your workflow rather than the cute graph, that's all.
I just checked the graphviz documentation and later versions, at least, allow for the generation of PNG files and may not allow for the generation of GIFs any more. If someone wants to play with this for 4.7, feel free - I'm hoping Lars will have time to redo a bunch of workflow anyway in 4.7.
But ... just to make sure everyone understands ... acs-workflow does not depend on graphviz, its use is entirely optional.
