When ever we would like to add a new rule on smartform "execute a smartobject method", sometime we didn't realize or forgot whether the current smartobject has existed or not. If a smartobject doesn't existed then we must chose to cancel it. And click "select a smartobjects" link again to refresh it.

I think it's a good idea to have a refresh feature (with right click on a category or folder one level above it) in order to refresh the latest smartobjects.