bug#1305: All code that currently beeps should use visual bell instead

[Gregory Heytings]

> Emacs beeps a lot if you do things that make it beep.  Like try to go 
> where no one has gone before.
>
> By contrast, other apps beep when they see fit.  A MUA plays sounds when 
> a new email arrives; the desktop beeps when it has some notification 
> that it thinks you must see and act upon, etc. etc.
>
> I don't see how Emacs is the odd one out here.

It just feels awkward by today's standards.

Emacs beeps when there is in fact no good reason to beep: whenever you 
type C-g, when isearch doesn't find a match, when you press C-p at BOB or 
C-n at EOB, when you press C-v or M-v too much (which can in fact be, for 
a short enough buffer: whenever you type C-v or M-v), when you press a 
self-inserting key in a read-only buffer, and so forth.  There is no good 
reason to beep, because (1) the echo area already contains an explanation 
about what happened, and (2) the error is not important enough to call the 
user's attention, nothing serious can happen if the user doesn't see it. 
In such cases flashing the echo area would be more than enough.

By contrast, Emacs doesn't beep when there would perhaps be a good reason 
to beep, for example when yes-or-no-p/y-or-n-p are called.

> And we are bikeshedding again: the opinions are clearly divided, and 
> Emacs lets each one of us customize this feature as they see fit.  So 
> why is arguing about the default so important, when there's clearly no 
> consensus?

We are discussing what a better default could be; in another thread the 
discussion is about a better default for the 'match' face.  Is discussing 
the default UX useless because everyone can customize everything?