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

[Gregory Heytings]

> > > And it turns the cursor red irreversibly in my config (but not in 
> > > 'emacs -Q').
> >
> > That's rather strange, color-bell--cursor-background is saved only 
> > once, when visual-bell is called for the first time.  I'll try to 
> > reproduce the issue, but some more detailed information (e.g. with 
> > debug-on-variable-change) would be welcome.
>
> I'll try bisecting when I have the time. In any case, it's just an 
> implementation bug, not a blocker.

Does the attached patch fix the problem in your config?  It is probably 
safer to check the cursor color each time color-bell is entered.

> > > Is nobody bothered by having this kind of visual indication while 
> > > 'visible-bell' is nil, though?
> >
> > It's easy to turn off, as indicated in NEWS: (setq ring-bell-function 
> > nil).
>
> I mean, like, semantically: this new proposal is also visual/visible.
>
> But 'visible-bell' is nil.

Yes, it's perhaps a bit unfortunate that "visible-bell" is nil in this 
case, but note that with visible-bell t and ring-bell-function ignore you 
also do not have what you could expect.  The semantics of visible-bell and 
ring-bell-function are a bit unclear, but they cannot be fixed anymore 
without introducing backward incompatible changes.

> > And IMO this is way better than the current situation, in which the 
> > default behavior depends on too many parameters that are outside the 
> > control of Emacs, in which the available options are different 
> > depending on the platform, and in which on certain platforms none of 
> > the available options are good.
>
> My #1 preference would be to make it all behave like (setq visible-bell 
> t) on GNU/Linux does. This way we both get a proven behavior with no 
> significant complaints, as well as consistency across platforms.

I understand that you're accustomed to what visible-bell t does on 
GNU/Linux, but frankly, its ugly.  Ask their opinion to non-Emacs users 
about that bell, I'd be surprised if they like it.

New-default-bell.patch
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