Returns an incoming message and leaves it in the queue.
True if the message was found and false if there was no incoming message waiting for handing
Return value is passed via res parameter.
MC_OK is always returned.
Call this method to peek the message from the input queue. This method returns immediately, returning the value that lets you determine whether there was a message in the queue. Upon return the message is NOT marked as being processed and the next call to PeekMessage will return the same message.
Once the message was processed, the application must call MessageProcessed method to let the Messenger send reply (if necessary) and cleanup internal records.
This method together with GetMessage and MessageProcessed is an alternative to using Queues.