Often after designing a process flow, I have to "walk through" what has been documented, to ensure there are no "dead ends", or lines not correctly joined, not described after a decision, or just to make sure the process actually makes sense; and I currently do this by zooming in, and manually tracing through the process (or printing it out and studying the process). A really useful feature would be a way to "simulate" the process, defining where it starts, then following it all the way through, one decision branch at a time (once that branch has been completed, going back to where the decision took place and following the next branch).