Yes Martin, you're right. That's very interesting.
I will add a custom collection to the EventArgs classes (EventResizeEventArgs, EventMoveEventArgs, etc.) that will be passed back to the client with the results. I've already planned to add a client-side handler that would be executed after the callback is finished. This handler will receive the collection and you will be able to decide what to do (showing "3 events modified", or "this move is not allowed" etc.).
I'm only not sure if it makes it into
4.0 SP4 release. But I will put it in the plans for
4.1.
Thanks for a nice suggestion!