Richard,

I think you missed my point. First, yes I did do that.

Second ("the point"):

I did this to use the same abstraction that was used extensively for other purposes, instead of recreating the same abstraction with a deque as its basis. Component reusability is one of the main points of OOP, after all...

And no, an item is not necessarily available - sometimes there is a message and sometimes there isn't. But if one was put into the queue, I claim that I should be able to rely on it being available right away in the application logic.