bug#16552: 24.3.50; regression: mouse-face does not turn off when move mouse away

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

This is with my setup.  I don't yet have a recipe from emacs -Q.

In this build:

1. If I move the mouse over multiple mouse-face zones of text, in a
buffer such as *Backtrace*, it behaves normally: the zone under the
mouse is highlighted, and other zones are unhighlighted.  That is,
when I move the mouse away from a zone it is unhighlighted.

2. But if I then click the title bar of another frame, and then move the
mouse over zones in the original frame, as the mouse moves into a zone
it is highlighted (which is normal), but as it moves out of a zone it is
not unhighlighted.  The effect is to highlight more and more zones as I
move the mouse.

(This is a regression.)


In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2014-01-23 on ODIEONE
Bzr revision: 116129 monnier@iro.umontreal.ca-20140123150141-qopqqhpm8jqo8a18
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/binary --enable-checking=yes,glyphs
 'CFLAGS=-O0 -g3' LDFLAGS=-Lc:/Devel/emacs/lib
 CPPFLAGS=-Ic:/Devel/emacs/include'