Re: bug in forward-visible-line: Patch

[Richard Stallman]

    BTW, one problem with the name `visiblep' is that it could be confused
    to mean the same thing as `pos-visible-in-window-p'.  OTOH, I don't
    think I don't think `invisiblep' has this problem, since the term of
    `invisible' in emacs is strongly associated with the invisible property.

I agree.  In addition, text is normally visible, and most text is
visible, so invisibility is an unusual situation.  That is another reason
why invisiblep is a better function to install.

I think this function is worth writing in C for speed.
Also, parts of it already exist in C, ISTR.