Hmm. I'm not inclined to move the text selection back into Annotator core, as I rather like the fact that the adder provides one interpretation of how a selection translates to an annotation, and others might have other interpretations (for example, limiting the granularity of a selection to a sentence or paragraph). Others might have entirely different interfaces, and might be annotating different media types (audio, imagery, video).

On the specific question of `interactionPoint`, I'm inclined to say that this is possibly general enough to include in core, and perhaps there should be a setter/getter pair for it (the setter is called both in the Adder and on highlight mouseover in the Viewer... not in the Highlighter, I was wrong).