Actually ... if we did it like that, then it would be possible to treat the signature + description + example(s) as one big table cell with line breaks rather than row-separator bars.
That would help address the inadequate-visual-separation-between-groups issue, but on the other hand maybe we'd end up with too little visual separation between the elements of a function description.
Speaking in terms of HTML if we use <hr /> instead of <br /> we would get the best of both worlds.
