title: Using enum property in a custom workflow activity
body: <p>I'm writing a custom workflow activity and would like to have some properties that are based on enums. However, I'm getting an error that seems to indicate that this isn't supported. So, first question, how would I setup a property that allowed the user of the workflow activity to select from a set of choices?</p>
  
  <p>And second, what types are allowed in a custom workflow activity (dependency properties that are available within the workflow designer)?</p>
  
  <p>Thanks!</p>