I recognize that you're making a point about which of the two came first.
Nevertheless this one, while dragging, makes discrete jumps that correspond to change events in the document. This makes it more like the widget in Wave. The one in Etherpad continuously follows the horizontal movement of the mouse, and jumps to the nearest discrete change point on mouse up.
I like the movement in Etherpad better, though. I might like it better if both were combined so that the real slider made continuous horizontal movements, and a shadow-pointer made discrete jumps while dragging.
