I've had a bit of time this week to dive into WF (formerly WWF... he he).  I'm very interested in utilizing this both professionally and personally.  In my experience, a HUGE amount of the software I interact with and write deals with workflow.  I need more than one hand to count the pieces of software I deal with at work that attempt to give the user a design surface to create workflow on.  Most of them fail pretty miserably.  That's why I was delighted that the WF designer was so extensible and reusable.

After orienting myself with the concepts of WF, I set out to extend the base SequentialWorkflow to wrap some custom behavior around the execution of the workflow.  I immediately ran into problems.  It seems that if you inherit from SequentialWorkflow, the project immediately thinks you are going to use the designer to create a workflow, rather than build a base type that will be used to build workflows in other projects.  It immediately starts throwing around validation messages like:

Activity 'BlahBlahBlah' validation failed: Property 'ID' not set.

Well, of course it's not set, I'm not even remotely trying to create one yet.  So, I add the following brain-dead code in the constructor:

if (this.DesignMode) {

      this.ID = "FakeID";

}

This gets rid of the validation error, but now it gripes that my class is not partial, so I slap a partial modifier on it and let it go.  Finally, it compiles.

Once I figure that out, I'm golden and things run fairly smoothly.