bug#3686: 23.1.50; Sticky mouse-face highlighting

1. Create the file ~/test.el with this content:

(setq diary-display-function 'diary-fancy-display
      diary-number-of-entries 7)

2. Create the file ~/diary with this content:

Jun 26, 2009 10:00 This is a test
Jun 27, 2009 10:00 This is a test
Jun 28, 2009 10:00 This is a test
Jun 29, 2009 10:00 This is a test

3. emacs -Q -l ~/test.el

4. `M-x diary' pops up a fancy diary buffer with this content (line
numbers added for subsequent reference):

1    Friday, June 26, 2009
2    =====================
3    10:00 This is a test
4    
5    Saturday, June 27, 2009
6    =======================
7    10:00 This is a test
8    
9    Sunday, June 28, 2009
10   =====================
11   10:00 This is a test
12   
13   Monday, June 29, 2009
14   =====================
15   10:00 This is a test
16

5. Move the mouse pointer over the fancy diary buffer.
=> As expected, line 3, 7, 11, and 15 have mouse-face highlighting when
   the mouse pointer moves over them.  However, lines 4, 8, and 12 (but
   not 16) also get mouse-face highlighting, and it remains when the
   mouse pointer moves off of those lines.

I suspect this bug is due to this change:

2009-06-22  Chong Yidong  <[email protected]>

	* w32term.c (x_draw_glyph_string): Use the glyph string's width
	rather than its background_width for drawing the overline and
	underline (Bug#489).

	* xterm.c (x_draw_glyph_string): Use the glyph string's width
	rather than its background_width for drawing the overline and
	underline (Bug#489).
	(xg_default_icon_file): New variable.
	(syms_of_xterm): Initialize it to the Emacs SVG icon file.
	(x_bitmap_icon): Under GTK, use xg_default_icon_file.

	* xdisp.c (Qbefore_string, Qafter_string): Add externs.
	(load_overlay_strings): Remove externs.
	(fast_find_position): Function deleted.
	(mouse_face_from_buffer_pos): New function, based on
	fast_find_position.  Correctly handle before-strings,
	display-strings, and after-strings (Bug#1220).
	(note_mouse_highlight): Use mouse_face_from_buffer_pos.

since it does not happen with my previous build before this change, but
I don't have time right now to confirm this by reverting the change.


In GNU Emacs 23.1.50.1 (i686-pc-linux-gnu, GTK+ Version 2.14.4)
 of 2009-06-23 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.10502000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=local
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t