--- a/man/ChangeLog	Mon May 24 10:43:29 2010 +0200
+++ b/man/ChangeLog	Fri May 28 13:48:22 2010 +0100
@@ -1,3 +1,12 @@
+2010-05-17  Jeff Sparkes  <jsparkes@gmail.com>
+
+	* lispref/windows.texi (Buffers and Windows):
+	Document buffer-display-count and buffer-display-time with
+	descriptions from GNU emacs lispref.
+
+	* lispref/locals.texi (Standard Buffer-Local Variables):
+	Add buffer-display-count and buffer-display-time.
+
 2010-04-03  Aidan Kehoe  <kehoea@parhasard.net>
 
 	* lispref/hash-tables.texi (Introduction to Hash Tables):

--- a/man/lispref/locals.texi	Mon May 24 10:43:29 2010 +0200
+++ b/man/lispref/locals.texi	Fri May 28 13:48:22 2010 +0100
@@ -25,9 +25,15 @@
 @item buffer-backed-up
 @pxref{Backup Files}
 
+@item buffer-display-count
+@xref{Buffers and Windows}.
+
 @item buffer-display-table
 @pxref{Display Tables}
 
+@item buffer-display-time
+@xref{Buffers and Windows}.
+
 @item buffer-file-format
 @pxref{Format Conversion}
 

--- a/man/lispref/windows.texi	Mon May 24 10:43:29 2010 +0200
+++ b/man/lispref/windows.texi	Fri May 28 13:48:22 2010 +0100
@@ -705,6 +705,12 @@
 @end example
 @end defun
 
+@defvar buffer-display-count
+This buffer-local variable records the number of times a buffer has been
+displayed in a window.  It is incremented each time
+@code{set-window-buffer} is called for the buffer.
+@end defvar
+
 @defun window-buffer &optional window
 This function returns the buffer that @var{window} is displaying.  If
 @var{window} is omitted, this function returns the buffer for the
@@ -729,6 +735,16 @@
 the same meaning as for @code{next-window}.
 @end defun
 
+
+@defvar buffer-display-time
+This variable records the time at which a buffer was last made visible
+in a window.  It is always local in each buffer; each time
+@code{set-window-buffer} is called, it sets this variable to
+@code{(current-time)} in the specified buffer (@pxref{Time of Day}).
+When a buffer is first created, @code{buffer-display-time} starts out
+with the value @code{nil}.
+@end defvar
+
 @node Displaying Buffers
 @section Displaying Buffers in Windows
 @cindex switching to a buffer

--- a/src/ChangeLog	Mon May 24 10:43:29 2010 +0200
+++ b/src/ChangeLog	Fri May 28 13:48:22 2010 +0100
@@ -3,6 +3,19 @@
 	* lread.c (read1): Accept #B<binary>, #O<octal>, and #X<hex>, just
 	like GNU Emacs.
 
+2010-05-17  Jeff Sparkes  <jsparkes@gmail.com>
+
+	* buffer.c (complex_vars_of_buffer):
+	Add buffer local variables buffer-display-count and
+	buffer-display-time.
+	(common_init_complex_vars_of_buffer):
+	Initialize them here.
+
+	* bufslots.h: Add slots for buffer-display-count and buffer-display-time.
+
+	* window.c (Fset_window_buffer): Update buffer-display-count and
+	buffer-display-time whenever a buffer is displayed.
+
 2010-05-16  Aidan Kehoe  <kehoea@parhasard.net>
 
 	Move `default-file-system-ignore-case' to C; pay attention to it

--- a/src/buffer.c	Mon May 24 10:43:29 2010 +0200
+++ b/src/buffer.c	Fri May 28 13:48:22 2010 +0100
@@ -2307,6 +2307,8 @@
 #ifdef MULE
     buffer_local_flags.category_table	= resettable;
 #endif
+    buffer_local_flags.display_time     = always_local_no_default;
+    buffer_local_flags.display_count    = make_int (0);
 
     buffer_local_flags.modeline_format		  = make_int (1<<0);
     buffer_local_flags.abbrev_mode		  = make_int (1<<1);
@@ -2800,6 +2802,18 @@
 set when a file is visited.  Automatically local in all buffers.
 */ );
 
+  DEFVAR_BUFFER_LOCAL ("buffer-display-count", display_count /*
+A number incremented each time this buffer is displayed in a window.
+The function `set-window-buffer' updates it.
+*/ );
+
+  DEFVAR_BUFFER_LOCAL ("buffer-display-time", display_time /*
+Time stamp updated each time this buffer is displayed in a window.
+The function `set-window-buffer' updates this variable
+to the value obtained by calling `current-time'.
+If the buffer has never been shown in a window, the value is nil.
+*/);
+
   DEFVAR_BUFFER_LOCAL_MAGIC ("buffer-invisibility-spec", invisibility_spec /*
 Invisibility spec of this buffer.
 The default is t, which means that text is invisible

--- a/src/bufslots.h	Mon May 24 10:43:29 2010 +0200
+++ b/src/bufslots.h	Fri May 28 13:48:22 2010 +0100
@@ -216,6 +216,12 @@
     /* The string generated by formatting the modeline in this buffer. */
     MARKED_SLOT (generated_modeline_string)
 
+    /* Incremented each time a buffer is displayed using set-window-buffer. */
+    MARKED_SLOT (display_count)
+
+    /* Last time this buffer was displayed using set-window-buffer. */
+    MARKED_SLOT (display_time)
+
     /* A hash table that maps from a "generic extent" (an extent in
        `modeline-format') into a buffer-specific extent. */
     MARKED_SLOT (modeline_extent_table)

--- a/src/lisp.h	Mon May 24 10:43:29 2010 +0200
+++ b/src/lisp.h	Fri May 28 13:48:22 2010 +0100
@@ -4554,6 +4554,7 @@
 EXFUN (Fbuffer_substring, 3);
 EXFUN (Fchar_after, 2);
 EXFUN (Fchar_to_string, 1);
+EXFUN (Fcurrent_time, 0);
 EXFUN (Fdelete_region, 3);
 EXFUN (Feobp, 1);
 EXFUN (Feolp, 1);

--- a/src/window.c	Mon May 24 10:43:29 2010 +0200
+++ b/src/window.c	Fri May 28 13:48:22 2010 +0100
@@ -3757,6 +3757,11 @@
 
       Fset_buffer (buffer);
     }
+  if (NILP (XBUFFER (buffer)->display_count))
+    XBUFFER (buffer)->display_count = make_int (1);
+  else
+    XBUFFER (buffer)->display_count = make_int (1 + XINT (XBUFFER (buffer)->display_count));
+  XBUFFER (buffer)->display_time = Fcurrent_time();
   return Qnil;
 }