I've started playing with WWF this week, and noticed something I noticed is that if you are defining a rule for an activity (say, a condition from an If's branch), and you add a predicate to it, the designer (in this case, the rules expression editor) uses the "this." syntax to refer to properties of the workflow class and it's methods.
However, it seems the designer will only allow you to use public properties and methods here, not private ones. Now, it would be really nice to be able to also use, say, private fields and still be able to access them from a condition in a rule. A good example here of why this would be useful is to be able to create a condition based on a property of a contained activity. Right now I'm getting around it by creating a forwarding property on the workflow itself, but seems a little bit too much work :)
If this will not be possible, then I'd sugguest dropping the use of "this." (or changing it to something else) to represent the workflow instance in the rules designer, since this will lead to an inconsistency to the underlying implementation language (i.e. in C# you'll be expecting this to be able to reference non-public members).
Any thoughts?