I see, but etherpads aren't always short and sweet. Often I find myself having to stop and start again, which means we need some sort of saving feature, as Mahz was talking about.

I wouldn't mind something as simple as what you depicted, an new reply box with invite capabilities with a small chat box, which would work best if it mimicked the PM system I think, instead of doing a tab, as there may be a need for multiple collabs to be happening at one time and I feel using a tab system would clutter the page, unless it was /etherpad/ tab and then the collab taking place in separate post boxes (ie: this as you're reading it).