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

[Gregory Heytings]

> In general, I like it

Thank you :-)

> (though the concerns about colors are still there; perhaps just use 
> inverse-video in GUI as well?).

You mean, do what (setq visual-bell t) does?  There's already an option 
for that...

> 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.

> 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).  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.