Hi Andy,
Sorry, getting WPF Studio 2009.1 took longer than expected to get out the door but we're very pleased with it. Now that it is out, we have started working on new features for our existing products. You can see in yesteday's maintenance release, we include a lot of updates to our existing WPF controls.
We haven't gotten to this particular feature yet. I know it's been out for a while... I'll make sure it's bumped up on the priority list so we can hopefully address it soon now that we're past the 2009.1 release.