Make calendar-mark-today update at midnight

[Stephen Berman]

Set today-visible-calendar-hook to 'calendar-mark-today in your
init-file or via Custom.  Then, if you have the calendar buffer open
before midnight and keep it open past the stroke of midnight, the
marked date remains unchanged, i.e., now yesterday is marked.  The
following patch makes the marked date change at midnight, i.e., keeps
today as the marked date, but I'm not sure it's the best way to deal
with this issue.

*** calendar.el~1.197~  2007-03-27 13:06:07.000000000 +0200
--- calendar.el         2007-03-30 00:06:05.000000000 +0200
***************
*** 2083,2089 ****
      (unwind-protect
          (if mark-diary-entries-in-calendar (mark-diary-entries))
        (if today-visible
!           (run-hooks 'today-visible-calendar-hook)
          (run-hooks 'today-invisible-calendar-hook)))))
  
  (defun generate-calendar (month year)
--- 2083,2092 ----
      (unwind-protect
          (if mark-diary-entries-in-calendar (mark-diary-entries))
        (if today-visible
!         (progn
!           (run-hooks 'today-visible-calendar-hook)
!           (and (memq 'calendar-mark-today today-visible-calendar-hook)
!                (run-at-time "24:00:00" nil 'redraw-calendar)))
          (run-hooks 'today-invisible-calendar-hook)))))
  
  (defun generate-calendar (month year)


In GNU Emacs 22.0.96.5 (i686-pc-linux-gnu, GTK+ Version 2.10.6)
 of 2007-03-27 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.70199902
configured using `configure  '--with-x-toolkit=gtk''

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
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Major mode: Diff

Minor modes in effect:
  which-function-mode: t
  tabbar-mwheel-mode: t
  tabbar-mode: t
  recentf-mode: t
  display-time-mode: t
  show-paren-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: identity

Recent input:
SPC J u d i t h SPC u n d SPC i c h SPC j o M-/ M-/ 
M-/ <backspace> <backspace> <backspace> <backspace> 
l a u M-/ M-/ SPC i m SPC H ü M-/ <help-echo> , SPC 
i c h SPC d u s c h e , SPC J u d i t h SPC d u s c 
h t <help-echo> <help-echo> <return> <tab> 9 . 0 3 
SPC w a x <backspace> <backspace> <backspace> e s c 
h M-/ , SPC E m a c M-/ <return> <tab> ~ 9 . 2 0 SPC 
J u d i t h SPC a u f SPC d i e SPC A r b e i t , SPC 
i c h SPC <up> <up> <right> <right> <right> <right> 
<right> <right> <right> , SPC i c h SPC F U t o n <left> 
<left> <left> <backspace> u <down> <down> S c h e r 
M-/ C-x 1 C-c j e <tab> <return> <S-right> C-c C-d 
<home> <next> <next> <next> <next> <down-mouse-5> <mouse-5> 
<double-down-mouse-5> <double-mouse-5> <down-mouse-5> 
<mouse-5> <down-mouse-1> <mouse-movement> <mouse-movement> 
<drag-mouse-1> <down-mouse-3> <mouse-3> <down-mouse-1> 
<mouse-1> <C-S-backspace> C-x C-s C-x C-f / u s <tab> 
e <tab> s <tab> c <tab> e <tab> / l i <tab> s <tab> 
/ c a l e <tab> c a l e <tab> <return> M-x e d i f 
f <return> <return> <up> <up> <up> <up> <return> n 
a n ! D <switch-frame> C-x 1 <switch-frame> <f1> <switch-frame> 
<switch-frame> <switch-frame> <switch-frame> <switch-frame> 
q y C-x o C-c C-d C-x o C-c C-d C-c C-d C-x o M-x <up> 
<return> C-g C-x o C-x C-s C-x o M-x <up> <return> 
<return> <up> <up> <up> <return> D <switch-frame> C-x 
o <switch-frame> <f1> M-x r e p o r <tab> b <tab> 
<return>

Recent messages:
Saving file /home/steve/.emacs.d/site-lisp/calendar.el...
Wrote /home/steve/.emacs.d/site-lisp/calendar.el
Reading file /users/steve/cvsroot/emacs/lisp/calendar/calendar.el ... 
Reading file /home/steve/.emacs.d/site-lisp/calendar.el ... 
Computing differences between calendar.el and calendar.el ...
Buffer A: Processing difference region 0 of 1
Buffer B: Processing difference region 0 of 1
Processing difference regions ... done
Auto-saving...done
Loading emacsbug...done