As with any Qt API, the Qt Declarative QML API that we expose needs to be carefully thought through to provide a consistent and intuitive developer experience.
One area of inconsistency has been the mixing of nouns and verbs. A declarative language describes what, not how. An example of this is the SetProperties element. This element describes the changes to one or more properties in a particular state. The SetProperties name has a distinctly imperative flavor. It implies an immediate action and fails to capture the nature of the element. Changes to properties in a state are merely overrides that will be restored when the state is left. These factors lead to the proposed renaming of SetProperties to PropertyChanges.
We are currently in the process of reviewing the entire QML element API. We expect the review to be complete by the end of August, though it may take a little longer for the proposed changes to propagate into the code. Unfortunately, if you are a Qt Declarative early adopter you will need to update your code. In order to help with this there is a list of changes and pending changes in the src/declarative/QmlChanges.txt file in the kinetic-declarativeui branch of the Kinetic repo.
BTW, if you've been experimenting with Qt Declarative we'd love to hear what you've been doing and how you've found using QML.