: Patch by Aaron Schrab <aaron@schrab.com>
: http://pug.schrab.com/aaron/mutt/

With this patch %?[ and %?( in index_format are treated as conditionals, if
the relevant time is less than 12 hours in the past or future, the part
before the next & will be evaluated, otherwise the part between that and the
next ? is evaluated.  So, I use as my index_format:

set index_format='%4C %Z %?[?%[%H:%M]&%[%m/%d]? %-15.15F (%5l) %s'

This produces entries like:

=<pre>
1153 rSF 01/10 To Mutt Users L (   50) -->Re: individual index_formats
1154   F 14:53 To Mutt Users L (   12)   `->
=</pre>

--- PATCHES~    Tue Nov  6 19:59:33 2001
+++ PATCHES     Tue Nov  6 19:59:42 2001
@@ -1,0 +1 @@
+patch-1.3.24.ats.date_optional.1
Index: hdrline.c
===================================================================
RCS file: /home/aarons/.cvsroot/mutt/hdrline.c,v
retrieving revision 1.1.1.5
diff -p -u -I$\(Author\|Date\|Header\|Id\|Locker\|Log\|Name\|RCSfile\|Revision\|Source\|State\)[:$] -r1.1.1.5 hdrline.c
--- hdrline.c	1999/09/14 07:08:59	1.1.1.5
+++ hdrline.c	1999/09/14 08:50:54
@@ -317,6 +317,14 @@ hdr_format_str (char *dest,
 
 	p = dest;
 
+	if (optional && (op == '[' || op == '(')) {
+	  T = time(NULL);
+	  T -= (op == '(') ? hdr->received : hdr->date_sent;
+	  if (T < -12 * 60 * 60 || T > 12 * 60 * 60)
+	    optional = 0;
+	  break;
+	}
+
 	cp = (op == 'd' || op == 'D') ? (NONULL (DateFmt)) : src;
 	if (*cp == '!')
 	{