I tried to find it out by exploring the code and it seems, that such fields are not supported. To be more specific I looked at PDChoiceField class which has one method - setValue . And it looks like this method always overrides previously set values, thus making multiple select impossible. Did I get it right?
P.S. I've posted this text in user mailing list 2 days ago, but nobody answered so far and I decided to post it here.
