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

[Drew Adams <drew.adams@oracle.com>]

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.

Seems to me like it was better before.  When you click a mouse button
sometimes the action you're interested in is actually bound to the down
event, not the up event.  And sometimes you're interested in
descriptions of both events.

And how else can you get to see the help for the command bound to the
down-button event?  I don't see how to do that now.

Also, I don't see anything in NEWS about this.  I do see this, however,
for `describe-key-briefly' (which is not what `C-h k' does) - perhaps it
is related to this undocumented change?

** 'describe-key-briefly' now ignores mouse movement events.


In GNU Emacs 26.0.90 (build 3, x86_64-w64-mingw32)
 of 2017-10-13 built on LAPHROAIG
Repository revision: 906224eba147bdfc0514090064e8e8f53160f1d4
Windowing system distributor 'Microsoft Corp.', version 6.1.7601
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