bug#22164: 25.0.50; Turning off blinking cursor mode makes menu tooltips behave erratically

[martin rudalics <rudalics@gmx.at>]

With emacs -Q evaluate (blink-cursor-mode -1).  Click the "File" entry
on the menu bar.  When I now move the mouse from one menu entry to
another it takes approximately 8 seconds until the tooltip is removed
from the previous entry and shown at the current one.

Reproducible at least since Emacs 24.2 and likely a Windows-only bug.
It might be related to this part of ‘blink-cursor-timer-function’

   ;; Suspend counting blinks when the w32 menu-bar menu is displayed,
   ;; since otherwise menu tooltips will behave erratically.
   (or (and (fboundp 'w32--menu-bar-in-use)
	   (w32--menu-bar-in-use))
       (setq blink-cursor-blinks-done (1+ blink-cursor-blinks-done)))

but I cannot imagine how that can have any effect when cursor blinking
is turned off.

In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
  of 2015-12-12
Repository revision: 06f00d39ff73e0c6c87ffb09ef3d67e8d3446b01
Windowing system distributor 'Microsoft Corp.', version 5.1.2600

martin