Hi,
Currently, I ported the UI component event themselves, not the Actual EventSystem ( confusing I know). So mouse over, dragging and similar is still something I have to digg and find a solution to bring to PlayMaker. Hopefully I'll find a solution soon.
The current proxy will be released with PlayMaker 1.8 and Unity 4.6 when it's out of beta. Too much mess on the new UI api to release anything to the public, as things break badly between releases, thing sare definitly not yet settled.
Bye,
Jean