Passing around the seek requester would mean adding the pointer to queueNewPlaypos, a new set of seek functions that aren't slots, adding it to doseek, creating a member variable in enginebuffer, and changing all of the seek functions in enginecontrol.  And, usually it would be NULL anyway because most seeks are done with signals.

Maybe I could have vinylcontrolcontrol save the playposition it wanted to seek to, and if it gets a seek matching that position, it knows that's the seek it queued?