bug#29478: 26.0.90; `C-h k' followed by mouse clicks no longer shows down event

[Eli Zaretskii <eliz@gnu.org>]

> From: Noam Postavsky <npostavs@users.sourceforge.net>
> Date: Mon, 27 Nov 2017 20:50:11 -0500
> Cc: Alan Mackenzie <acm@muc.de>, 29478@debbugs.gnu.org
> 
> Drew Adams <drew.adams@oracle.com> writes:
> 
> > The down mouse-button event is no longer listed along with the up
> > event when you use `C-h k' with a click event.  Dunno whether this was
> > by design or is an oversight.
> 
> Looks like oversight.  Possibly related to Bug#29272.  The following
> seems to fix it for me, but I'm having trouble convincing myself that
> it's the right thing.
> 
> --- c/lisp/help.el
> +++ i/lisp/help.el
> @@ -738,7 +738,7 @@ help-read-key-sequence
>                           ;; spuriously trigger the `sit-for'.
>                           (sleep-for 0.01)
>                           (while (read-event nil nil 0.01))
> -                         (not (sit-for (/ double-click-time 1000.0) t))))))))
> +                         (sit-for (/ double-click-time 1000.0) t)))))))
>            (list
>             key
>             ;; If KEY is a down-event, read and include the
> 

Not an oversight: the above patch brings back bug#29272.