Raised by: Dominic in mail.
Discussion: Dominic: An earlier draft had the ability to set lastMark, but now it looks like it's read-only, is that correct? That actually may be easier to implement, because many speech engines don't support seeking to the middle of a speech stream without first synthesizing the whole thing.
Michael: Actually the speech xg version has never supported setting a lastMark. You can control playback using the normal media controls (setting currentTime, seekable, seeking, etc.).
Resolution: Leave as is for now. Add issue note to lastMark saying it might be nice to set on this, but functionality is complex.