link appearance (again) (was: RE: Docstring line length)

[Drew Adams]

    > A note: Underlined blue is the most common way to tell
    > something is a link
    > on a web page. On quite a lot of pages I have seen underlined
    > black text
    > who are not links (this is in my opinion quite confusing and I do not
    > recommend it, but I have seen it).

    I agree.  I see no reason for Help links to have a different appearance
    than Info links and Web links.

We've been through this before..., but add my vote (again) for underlined
blue foreground, for links - as is the case now in Info. Links are not the
same as buttons (even if we use a `button' face to implement them).

I would make an exception in buffers that are link-dense - that is,
essentially tables or lists of links. Such buffers include Dired, Buffer
List, Occur, and compilation (e.g. grep). Almost everything in such a buffer
is a link (or it should be).

In such buffers, I would prefer to see the whole line be a link (although,
where appropriate, it could be divided into more than one link, with
different destinations). And I would propose _not_ using any face to
indicate such links. The mouse-face is enough to indicate a link, because
the mouse is nearly always over some link in a link-dense buffer. The
mouse-face should then be an underline (perhaps blue) - that is, it should
look like a link.