bug#42865: 28.0.50; Add new 'copy-region-quietly' defcustom

[Juri Linkov]

>> Then like 'signal' uses 'ERROR-SYMBOL' as an error symbol, not string,
>> 'user-message' should use a symbol as well, e.g. in 'indicate-copied-region':
>>
>>   (user-message
>>    'indicate-copied-region
>>    "Saved text until \"%s\"" (buffer-substring-no-properties (- mark len) 
>> mark))
>>
>> then users put a property on that symbol:
>>
>>   (put 'indicate-copied-region 'inhibit-message t)
>>
>> to disable the message.
>
> Or we could have inhibit-message also be a list of symbols to inhibit?

Or a list of regexps for those users who want to inhibit message strings
directly by a regexp instead of messing with an intermediate layer of symbols :)

IOW, I still prefer the simplicity of such regexps as

  (add-to-list 'inhibit-message "^Saved text until")

and can't imagine a situation why I'd want to inhibit such message
for one command but not for another.