bug#23419: 25.0.93; double-click-time

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Fri, 14 Aug 2020 20:49:18 -0700
> Cc: 23419@debbugs.gnu.org
> 
> In the attached patch I add a new function `mouse-double-click-time'
> which always returns a number.  This seems better than adding
> specialized logic everywhere to handle the various cases.

I don't see how this resolves the issue pointed out by Martin.  How do
we know that the problematic callers will DTRT with the arbitrary
values your function returns for t and nil?  Using a very large number
for t may be a good approximation (although I'm not even sure in that
case), but using zero for nil?

I'm afraid there's no way around auditing each caller and determining
what those non-numerical values mean in each case.  For example, I'd
actually suggest to avoid the call to sit-for in the nil case, because
a double-click will never be "on the way" in that case.

Thanks.