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

[Stefan Monnier]

>> FWIW, I don't see what's "intrusive" about the "blink top and bottom lines of
>> the selected frame" which I currently see in GNU/Linux.
> In this Emacs, it blinks the two topmost lines.  Which may be a bug?

My crystal ball tells me it's a hidpi bug, indeed: it probably doubles
something where it shouldn't, so at the top, it turns into 1 line into
2 and at the bottom, the line ends up being twice too far (and probably
twice too think as well, but we don't get to see it anyway).

>> It may not be slick but it does the job and I don't find it intrusive.
>> Of course, I'm biased (I've used it for too many years), but it's
>> clearly less intrusive than the non-visual bell.
> It's more intrusive than what many people are using -- which is neither
> an audible nor a visible bell, but just the echo area saying "Quit" when
> you hit `C-g' (etc).

But those people won't be affected by a change in the default.
The only people which would see a "more intrusive" bell is those who
keep the default settings but whose environment ends up muting the
audible bell.  I don't know how common this is.


        Stefan