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+;;; msb.el --- Customizable buffer-selection with multiple menus.
+;; Copyright (C) 1993, 1994 Lars Lindberg <Lars.Lindberg@sypro.cap.se>
+;;
+;; Author: Lars Lindberg <Lars.Lindberg@sypro.cap.se>
+;; Created: 8 Oct 1993
+;; $Revision: 3.21 $
+;; $Date: 1994/12/22 07:58:27 $
+;; Keywords: mouse buffer menu 
+;;
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2 of the License, or
+;; (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program; if not, write to the Free Software
+;; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+;; LCD Archive Entry:
+;; msb|Lars Lindberg|Lars.Lindberg@sypro.cap.se|
+;; Choose buffer with the mouse.
+;; $Date: 1994/12/22 07:58:27 $|$Revision: 3.21 $|~/packages/msb.el.Z|
+
+;;; Commentary:
+;;
+;; Purpose of this package:
+;;   1. Offer a function for letting the user choose buffer,
+;;      not necessarily for switching to it.
+;;   2. Make a better mouse-buffer-menu.
+;;
+;; Installation:
+;;   (require 'msb)
+;;   Note! You now use msb instead of mouse-buffer-menu.
+;;
+;;   Now try c-mouse-down-1 (Press <CTRL> and mouse button 1 at the
+;;   same time).
+;;
+;; Customization:
+;;   Look at the variable 'msb-menu-cond' for deciding what menus you
+;;   want. It's not that hard to customize, despite my not-so-good
+;;   doc-string. Feel free to send me a better doc-string.
+;;   There are some constants for you to try here:
+;;   msb--few-menus
+;;   msb--very-many-menus (default)
+;;   
+;;   Look at the variable 'msb-item-handling-function' for customization
+;;   of the appearance of every menu item. Try for instance setting
+;;   it to 'msb-alon-item-handler.
+;;   
+;;   Look at the variable 'msb-item-sort-function' for customization
+;;   of sorting the menus. Set it to t for instance, which means no
+;;   sorting - you will get latest used buffer first.
+;;
+;;   Also check out the variable 'msb-display-invisible-buffers-p'
+
+;; Known bugs:
+;; - `msb' does not work on a non-X-toolkit Emacs.
+;; Future enhancements:
+;; - [Mattes] had a suggestion about sorting files by extension.
+;;   I (Lars Lindberg) think this case could be solved if msb.el was
+;;   rewritten to handle more dynamic splitting.  It's now completely
+;;   static, depending on the menu-cond.  If the splitting could also
+;;   be done by a user-defined function a lot of cases would be
+;;   solved.
+;; - [Jim] suggested that the Frame menu became a part of the buffer menu.
+
+;;; Change Log
+;; 3.21 22/12-94
+;;	Fixed bug that occured in non X-toolkit versions of Emacs.
+;;	[Chalupsky] pointed out that a global `save-match-data' is
+;;	necessary.
+;;	Bug found.  Thanks [kifer].
+;; 3.16 20/12-94
+;;	Added separators to the menu.  New variable `msb-separator-diff'.
+;;	New variable `msb-files-by-directory-sort-key'.
+;;	Removed `msb--many-menus.'
+;;	Fixed bugs.
+;; 3.13 20/12-94
+;;	Menu fix for non-X-toolkit Emacsen and new "process"
+;;	menu. Thanks [jim].
+;;      Bug for 'files-by-type'.
+;;	Restored the call to `msb-after-load-hooks'.  Thanks [larry].
+;;      Major fixes by [Ake].
+;;      Menu-bar buffer-menu now has menu-toggle at top level.
+;;  3.6 16/12-94
+;;	Added variable `msb-max-file-menu-items'.
+;;	Removed a large part of the change log.
+;;	Found bug.
+;;  3.3 16/12-94
+;;      Found bugs.
+;;  3.1 16/12-94
+;;      Now has two types of menus - "files by directory" and "files
+;;      by type".
+;;      Added variable `msb-files-by-directory'.
+;;      Fixed a number of bugs for older versions.
+;;  2.11 16/12-94
+;;      Added 'no-multi to msb-menu-cond.
+;;      Added possibility to shift the menu leftwards. Thanks [kifer].
+;;  2.8 15/12-94
+;;      Now aware of earlier versions of Emacs that doesn't have the
+;;      function `frame-or-buffer-changed-p' or the variable
+;;      `menu-bar-update-hook'.  Thanks [will].
+;;  2.7 14/12-94
+;;	Better installation.
+;;  2.6 14/12-94
+;;	Now only makes up the menu when necessary.
+;;	Added menu-bar support.
+;;	Now handles errors in msb-menu-cond better. Thanks [jaalto].
+;;      Added MH-awareness. Thanks [kifer].
+;;      Added autoload statements.
+;;  2.3 8/12-94
+;;  	Now uses RCS version numbering for msb.el version number.
+;;  	Submitted this to LCD.
+
+;;; Thanks goes to
+;;  [msb] - Mark Brader <msb@sq.com>
+;;  [Chalupsky] - Hans Chalupsky <hans@cs.Buffalo.EDU>
+;;  [jim] - Jim Berry <m1jhb00@FRB.GOV>
+;;  [larry] - Larry Rosenberg <ljr@ictv.com>
+;;  [will] - Will Henney <will@astroscu.unam.mx>
+;;  [jaalto] - Jari Aalto <jaalto@tre.tele.nokia.fi>
+;;  [kifer] - Michael Kifer <kifer@sbkifer.cs.sunysb.edu>
+;;  [Gael] - Gael Marziou <gael@gnlab030.grenoble.hp.com>
+;;  [Gillespie] - Dave Gillespie <daveg@thymus.synaptics.com>
+;;  [Alon] - Alon Albert <alon@milcse.rtsg.mot.com>
+;;  [KevinB] - Kevin Broadey, <KevinB@bartley.demon.co.uk>
+;;  [Ake] - Ake Stenhof <ake@cadpoint.se>
+;;  [RMS] - Richard Stallman <rms@gnu.ai.mit.edu>
+;;  [Fisk] - Steve Fisk <fisk@medved.bowdoin.edu>
+
+;;; Code:
+
+(require 'cl)
+
+;;;
+;;; Some example constants to be used for 'msb-menu-cond'. See that
+;;; variable for more information. Please note that if the condition
+;;; returns 'multi, then the buffer can appear in several menus.
+;;;
+(defconst msb--few-menus
+  '(((and (boundp 'server-buffer-clients)
+	  server-buffer-clients
+	  'multi)
+     3030
+     "Clients (%d)")
+    ((and msb-display-invisible-buffers-p
+	  (msb-invisible-buffer-p)
+	  'multi)
+     3090
+     "Invisible buffers (%d)")
+    ((eq major-mode 'dired-mode)
+     2010
+     "Dired (%d)"
+     msb-dired-item-handler
+     msb-sort-by-directory)
+    ((eq major-mode 'Man-mode)
+     4090
+     "Manuals (%d)")
+    ((eq major-mode 'w3-mode)
+     4020
+     "WWW (%d)")
+    ((or (memq major-mode '(rmail-mode vm-summary-mode vm-mode mail-mode))
+	 (memq major-mode '(mh-letter-mode
+			    mh-show-mode
+			    mh-folder-mode))	 
+	 (memq major-mode '(gnus-summary-mode
+			    news-reply-mode
+			    gnus-group-mode
+			    gnus-article-mode
+			    gnus-kill-file-mode
+			    gnus-browse-killed-mode)))
+     4010
+     "Mail (%d)")
+    ((not buffer-file-name)
+     4099
+     "Buffers (%d)")
+    ('no-multi
+     1099
+     "Files (%d)")))
+
+(defconst msb--very-many-menus
+  '(((and (boundp 'server-buffer-clients)
+	  server-buffer-clients
+	  'multi)
+     1010
+     "Clients (%d)")
+    ((and (boundp 'vc-mode) vc-mode 'multi)
+     1020
+     "Version Control (%d)")
+    ((and buffer-file-name
+	  (buffer-modified-p)
+	  'multi)
+     1030
+     "Changed files (%d)")
+    ((and (get-buffer-process (current-buffer))
+	  'multi)
+     1040
+     "Processes (%d)")
+    ((and msb-display-invisible-buffers-p
+	  (msb-invisible-buffer-p)
+	  'multi)
+     1090
+     "Invisible buffers (%d)") 
+    ((eq major-mode 'dired-mode)
+     2010
+     "Dired (%d)"
+     ;; Note this different menu-handler
+     msb-dired-item-handler
+     ;; Also note this item-sorter
+     msb-sort-by-directory)
+    ((eq major-mode 'Man-mode)
+     4030
+     "Manuals (%d)")
+    ((eq major-mode 'w3-mode)
+     4020
+     "WWW (%d)")
+    ((or (memq major-mode '(rmail-mode vm-summary-mode vm-mode mail-mode))
+	 (memq major-mode '(mh-letter-mode
+			    mh-show-mode
+			    mh-folder-mode))	 
+	 (memq major-mode '(gnus-summary-mode
+			    news-reply-mode
+			    gnus-group-mode
+			    gnus-article-mode
+			    gnus-kill-file-mode
+			    gnus-browse-killed-mode)))
+     4010
+     "Mail (%d)")
+    ;; Catchup for all non-file buffers
+    ((and (not buffer-file-name)
+	  'no-multi)
+     4099
+     "Other non-file buffers (%d)")
+    ((and (string-match "/\\.[^/]*$" buffer-file-name)
+	  'multi)
+     3090
+     "Hidden Files (%d)")
+    ((memq major-mode '(c-mode c++-mode))
+     3010
+     "C/C++ Files (%d)")
+    ((eq major-mode 'emacs-lisp-mode)
+     3020
+     "Elisp Files (%d)")
+    ((eq major-mode 'latex-mode)
+     3030
+     "LaTex Files (%d)")
+    ('no-multi
+     3099
+     "Other files (%d)")))
+
+;; msb--many-menus is obsolete
+(defvar msb--many-menus msb--very-many-menus)
+
+;;;
+;;; Customizable variables
+;;;
+
+(defvar msb-separator-diff 100
+  "*Non-nil means use separators.
+The separators will appear between all menus that have a sorting key that differs by this value or more.")
+
+(defvar msb-files-by-directory-sort-key 0
+  "*The sort key for files sorted by directory")
+
+(defvar msb-max-menu-items 25
+  "*The maximum number of items in a menu.
+If this variable is set to 15 for instance, then the 15 latest used
+buffer that fits in a certain submenu will appear in that submenu.
+Nil means no limit.")
+
+(defvar msb-max-file-menu-items 10
+  "*The maximum number of items from different directories.
+
+When the menu is of type 'file by directory', this is the maximum
+number of buffers that are clumped togehter from different
+directories.
+
+If the value is not a number, then the value 10 is used.")
+
+(defvar msb-most-recently-used-sort-key -1010
+  "*Where should the menu with the most recently used buffers be placed?")
+
+(defvar msb-display-most-recently-used t
+  "*How many buffers should be in the most-recently-used menu.
+No buffers at all if less than 1 or nil.
+T means use the value of `msb-max-menu-items' in the way it is defined.")
+
+(defvar msb-most-recently-used-title "Most recently used (%d)"
+  "*The title for the most-recently-used menu.")
+  
+(defvar msb-horizontal-shift-function '(lambda () 0)
+  "*Function that specifies a number of pixels by which the top menu should
+be shifted leftwards.")
+
+(defvar msb-display-invisible-buffers-p nil
+  "*Show invisible buffers or not.
+Non-nil means that the buffer menu should include buffers that have
+names that starts with a space character.")
+
+(defvar msb-item-handling-function 'msb-item-handler
+  "*The appearance of a buffer menu.
+
+The default function to call for handling the appearance of a menu
+item. It should take to arguments, BUFFER and MAX-BUFFER-NAME-LENGTH,
+where the latter is the max length of all buffer names.
+When the function is called, BUFFER is the current buffer.
+This function is called for items in the variable 'msb-menu-cond' that
+have nil as ITEM-HANDLING-FUNCTION. See 'msb-menu-cond' for more
+information.")
+
+(defvar msb-item-sort-function 'msb-sort-by-name
+  "*The order of items in a buffer menu.
+The default function to call for handling the order of items in a menu
+item. This function is called like a sort function. The items
+look like (ITEM-NAME . BUFFER).
+ITEM-NAME is the name of the item that will appear in the menu.
+BUFFER is the buffer, this is not necessarily the current buffer.
+
+Set this to nil or t if you don't want any sorting (faster).")
+
+(defvar msb-files-by-directory nil
+  "*Non-nil means that files should be sorted by directory instead of
+the groups in msb-menu-cond.")
+
+(defvar msb-menu-cond msb--very-many-menus
+  "*List of criterias for splitting the mouse buffer menu.
+The elements in the list should be of this type:
+ (CONDITION MENU-SORT-KEY MENU-TITLE ITEM-HANDLING-FN ITEM-SORT-FN).
+
+When making the split, the buffers are tested one by one against the
+CONDITION, just like a lisp cond: When hitting a true condition, the
+other criterias are *not* tested and the buffer name will appear in
+the menu with the menu-title corresponding to the true condition.
+
+If the condition returns the symbol 'multi, then the buffer will be
+added to this menu *and* tested for other menus too.  If it returns
+'no-multi, then the buffer will only be added if it hasn't been added
+to any other menu.
+
+During this test, the buffer in question is the current buffer, and
+the test is surrounded by calls to `save-excursion' and
+`save-match-data'
+
+The categories are sorted by MENU-SORT-KEY. Smaller keys are on
+top. nil means don't display this menu.
+
+MENU-TITLE is really a format. If you add %d in it, the %d is replaced
+with the number of items in that menu.
+
+ITEM-HANDLING-FN, is optional. If it is supplied and is a
+function, than it is used for displaying the items in that particular
+buffer menu, otherwise the function pointed out by
+'msb-item-handling-function' is used.
+
+ITEM-SORT-FN, is also optional.
+If it is not supplied, the function pointed out by
+'msb-item-sort-function' is used.
+If it is nil, then no sort takes place and the buffers are presented
+in least-recently-used order.
+If it is t, then no sort takes place and the buffers are presented in
+most-recently-used order.
+If it is supplied and non-nil and not t than it is used for sorting
+the items in that particular buffer menu.
+
+Note1: There should always be a 'catch-all' as last element,
+in this list. That is an element like (t TITLE ITEM-HANDLING-FUNCTION).
+Note2: A buffer menu appears only if it has at least one buffer in it.
+Note3: If you have a CONDITION that can't be evaluated you will get an
+error every time you do \\[msb].")
+
+(defvar msb-after-load-hooks nil
+  "Hooks to be run after the msb package has been loaded.")
+
+;;;
+;;; Internal variables
+;;;
+
+;; The last calculated menu.
+(defvar msb--last-buffer-menu nil)
+
+;; If this is non-nil, then it is a string that describes the error.
+(defvar msb--error nil)
+
+;;;
+;;; Some example function to be used for 'msb-item-sort-function'.
+;;;
+(defun msb-item-handler (buffer &optional maxbuf)
+  "Create one string item, concerning BUFFER, for the buffer menu.
+The item looks like:
+*% <buffer-name>
+The '*' appears only if the buffer is marked as modified.
+The '%' appears only if the buffer is read-only.
+Optional second argument MAXBUF is completely ignored."
+  (let ((name (buffer-name))
+	(modified (if (buffer-modified-p) "*" " "))
+	(read-only (if buffer-read-only "%" " ")))
+    (format "%s%s %s" modified read-only name)))
+
+
+(eval-when-compile (require 'dired))
+
+;; 'dired' can be called with a list of the form (directory file1 file2 ...)
+;; which causes 'dired-directory' to be in the same form.
+(defun msb--dired-directory ()
+  (cond ((stringp dired-directory)
+	 (abbreviate-file-name (expand-file-name dired-directory)))
+	((consp dired-directory)
+	 (abbreviate-file-name (expand-file-name (car dired-directory))))
+	(t
+	 (error "Unknown type of 'dired-directory' in buffer %s"
+		(buffer-name)))))
+
+(defun msb-dired-item-handler (buffer &optional maxbuf)
+  "Create one string item, concerning a dired BUFFER, for the buffer menu.
+The item looks like:
+*% <buffer-name>
+The '*' appears only if the buffer is marked as modified.
+The '%' appears only if the buffer is read-only.
+Optional second argument MAXBUF is completely ignored."
+  (let ((name (msb--dired-directory))
+	(modified (if (buffer-modified-p) "*" " "))
+	(read-only (if buffer-read-only "%" " ")))
+    (format "%s%s %s" modified read-only name)))
+
+(defun msb-alon-item-handler (buffer maxbuf)
+  "Create one string item for the buffer menu.
+The item looks like:
+<buffer-name> *%# <file-name>
+The '*' appears only if the buffer is marked as modified.
+The '%' appears only if the buffer is read-only.
+The '#' appears only version control file (SCCS/RCS)."
+  (format (format "%%%ds  %%s%%s%%s  %%s" maxbuf)
+          (buffer-name buffer)
+          (if (buffer-modified-p) "*" " ")
+          (if buffer-read-only "%" " ")
+          (if (and (boundp 'vc-mode) vc-mode) "#" " ")
+          (or buffer-file-name "")))
+
+;;;
+;;; Some example function to be used for 'msb-item-handling-function'.
+;;;
+(defun msb-sort-by-name (item1 item2)
+  "Sorts the items depending on their buffer-name
+An item look like (NAME . BUFFER)."
+  (string-lessp (buffer-name (cdr item1))
+		(buffer-name (cdr item2))))
+
+
+(defun msb-sort-by-directory (item1 item2)
+  "Sorts the items depending on their directory. Made for dired.
+An item look like (NAME . BUFFER)."
+  (string-lessp (save-excursion (set-buffer (cdr item1)) (msb--dired-directory))
+		(save-excursion (set-buffer (cdr item2)) (msb--dired-directory))))
+
+;;;
+;;; msb
+;;;
+;;; This function can be used instead of (mouse-buffer-menu EVENT)
+;;; function in "mouse.el".
+;;; 
+(defun msb (event)
+  "Pop up several menus of buffers for selection with the mouse.
+This command switches buffers in the window that you clicked on, and
+selects that window.
+
+See the function 'mouse-select-buffer' and the variable
+'msb-menu-cond' for more information about how the menus are split."
+  (interactive "e")
+  (let ((buffer (mouse-select-buffer event))
+	(window (posn-window (event-start event))))
+    (cond
+     (buffer
+      (or (framep window) (select-window window))
+      (switch-to-buffer (car (cdr buffer))))))
+  nil)
+
+;;;
+;;; Some supportive functions
+;;;
+(defun msb-invisible-buffer-p (&optional buffer)
+  "Return t if optional BUFFER is an \"invisible\" buffer.
+If the argument is left out or nil, then the current buffer is considered."
+  (and (> (length (buffer-name buffer)) 0)
+       (eq ?\ (aref (buffer-name buffer) 0))))
+
+;; Strip one hierarcy level from the end of PATH.
+(defun msb--strip-path (path)
+  (save-match-data
+    (if (string-match "\\(.+\\)/[^/]+$" path)
+	(substring path (match-beginning 1) (match-end 1))
+      "/")))
+
+;; Create an alist with all buffers from LIST that lies under the same
+;; directory will be in the same item as the directory string as
+;;'((PATH1 . (BUFFER-1 BUFFER-2 ...)) (PATH2 . (BUFFER-K BUFFER-K+1...)) ...)
+(defun msb--init-file-alist (list)
+  (let ((buffer-alist
+	 (sort (mapcan
+		(function
+		 (lambda (buffer)
+		   (let ((file-name (buffer-file-name buffer)))
+		     (when file-name
+		       (list (cons (msb--strip-path file-name) buffer))))))
+		list)
+	       (function (lambda (item1 item2)
+			   (string< (car item1) (car item2)))))))
+    ;; Make alist that looks like
+    ;;'((PATH1 . (BUFFER-1 BUFFER-2 ...)) (PATH2 . (BUFFER-K)) ...)
+    (let ((path nil)
+	  (buffers nil)
+	  (result nil))
+      (append
+       (mapcan (function
+	       (lambda (item)
+		 (cond
+		  ((and path
+			msb-max-menu-items
+			(< (length buffers) msb-max-menu-items)
+			(string= path (car item)))
+		   (push (cdr item) buffers)
+		   nil)
+		  (t
+		   (when path
+		     (setq result (cons path buffers)))
+		   (setq path (car item))
+		   (setq buffers (list (cdr item)))
+		   (and result (list result))))))
+	      buffer-alist)
+       (list (cons path buffers))))))
+
+;; Choose file-menu with respect to directory for every buffer in LIST.
+(defun msb--choose-file-menu (list)
+  (let ((buffer-alist (msb--init-file-alist list))
+	(final-list nil)
+	(max-clumped-together (if (numberp msb-max-file-menu-items)
+				  msb-max-file-menu-items
+				10))
+	(top-found-p nil)
+	(last-path nil)
+	first rest path buffers)
+    (setq first (car buffer-alist))
+    (setq rest (cdr buffer-alist))
+    (setq path (car first))
+    (setq buffers (cdr first))
+    (while rest
+      (let ((found-p nil)
+	    (tmp-rest rest)
+	    new-path item)
+	(setq item (car tmp-rest))
+	(while (and tmp-rest
+		    (<= (length buffers) max-clumped-together)
+		    (>= (length (car item)) (length path))
+		    (string= path (substring (car item) 0 (length path))))
+	  (setq found-p t)
+	  (setq buffers (append buffers (cdr item)))
+	  (setq tmp-rest (cdr tmp-rest))
+	  (setq item (car tmp-rest)))
+	(cond
+	 ((> (length buffers) max-clumped-together)
+	  (setq last-path (car first))
+	  (when top-found-p
+	    (setq first (cons (concat (car first) "/...")
+			      (cdr first)))
+	    (setq top-found-p nil))
+	  (push first final-list)
+	  (setq first (car rest)
+		rest (cdr rest))
+	  (setq path (car first)
+		buffers (cdr first)))
+	 (t
+	  (when found-p
+	    (setq top-found-p t)
+	    (setq first (cons path buffers)
+		  rest tmp-rest))
+	  (setq path (msb--strip-path path)
+		buffers (cdr first))
+	  (when (and last-path
+		     (or (and (>= (length path) (length last-path))
+			      (string= last-path
+				       (substring path 0 (length last-path))))
+			 (and (< (length path) (length last-path))
+			      (string= path
+				       (substring last-path 0 (length path))))))
+			 
+	    (when top-found-p
+	      (setq first (cons (concat (car first) "/...")
+				(cdr first)))
+	      (setq top-found-p nil))
+	    (push first final-list)
+	    (setq first (car rest)
+		  rest (cdr rest))
+	    (setq path (car first)
+		buffers (cdr first)))))))
+    (when top-found-p
+      (setq first (cons (concat (car first)
+				(if (string-match "/$" (car first))
+				    "..."
+				  "/..."))
+			(cdr first)))
+      (setq top-found-p nil))
+    (push first final-list)
+    (nreverse final-list)))
+
+;; Create a vector as:
+;; [BUFFER-LIST-VARIABLE CONDITION MENU-SORT-KEY MENU-TITLE ITEM-HANDLER SORTER)
+;; from an element in 'msb-menu-cond'. See that variable for a
+;; description of it's elements.
+(defun msb--create-function-info (menu-cond-elt)
+  (let* ((list-symbol (make-symbol "-msb-buffer-list"))
+	 (tmp-ih (and (> (length menu-cond-elt) 3)
+		      (nth 3 menu-cond-elt)))
+	 (item-handler (if (and tmp-ih (fboundp tmp-ih))
+			   tmp-ih
+			 msb-item-handling-function))
+	 (tmp-s (if (> (length menu-cond-elt) 4)
+		    (nth 4 menu-cond-elt)
+		  msb-item-sort-function))
+	 (sorter (if (or (fboundp tmp-s)
+			 (null tmp-s)
+			 (eq tmp-s 't))
+		    tmp-s
+		   msb-item-sort-function)))
+    (when (< (length menu-cond-elt) 3)
+      (error "Wrong format of msb-menu-cond."))
+    (when (and (> (length menu-cond-elt) 3)
+	       (not (fboundp tmp-ih)))
+      (signal 'invalid-function (list tmp-ih)))
+    (when (and (> (length menu-cond-elt) 4)
+	       tmp-s
+	       (not (fboundp tmp-s))
+	       (not (eq tmp-s 't)))
+      (signal 'invalid-function (list tmp-s)))
+    (set list-symbol '())
+    (vector list-symbol			;BUFFER-LIST-VARIABLE
+	    (nth 0 menu-cond-elt)	;CONDITION
+	    (nth 1 menu-cond-elt)	;SORT-KEY
+	    (nth 2 menu-cond-elt)	;MENU-TITLE
+	    item-handler		;ITEM-HANDLER
+	    sorter)			;SORTER
+    ))
+
+;; This defsubst is only used in `msb--choose-menu' below.  It was
+;; pulled out merely to make the code somewhat clearer. The indention
+;; level was too big.
+(defsubst msb--collect (function-info-vector)
+  (let ((result nil)
+	(multi-flag nil)
+	function-info-list)
+    (setq function-info-list
+	  (loop for fi
+		across function-info-vector
+		if (and (setq result
+			      (eval (aref fi 1))) ;Test CONDITION
+			(not (and (eq result 'no-multi)
+				  multi-flag))
+			(progn (when (eq result 'multi)
+				 (setq multi-flag t))
+			       t)
+			(or (not msb-max-menu-items)
+			    (< (length (eval (aref fi 0)))
+			       msb-max-menu-items)))
+		collect fi
+		until (and result
+			   (not (eq result 'multi)))))
+    (when (and (not function-info-list)
+	       (not result))
+      (error "No catch-all in msb-menu-cond!"))
+    function-info-list))
+
+;; Adds BUFFER to the menu depicted by FUNCTION-INFO
+;; All side-effects.  Adds an element of type '(BUFFER-TITLE . BUFFER)
+;; to the buffer-list variable in function-info.
+(defun msb--add-to-menu (buffer function-info max-buffer-name-length)
+  (let ((list-symbol (aref function-info 0))) ;BUFFER-LIST-VARIABLE
+    ;; Here comes the hairy side-effect!
+    (set list-symbol
+	 (cons (cons (funcall (aref function-info 4) ;ITEM-HANDLER
+			      buffer
+			      max-buffer-name-length)
+		     buffer)
+	       (eval list-symbol)))))
+  
+;; Selects the appropriate menu for BUFFER.
+;; This is all side-effects, folks!
+;; This should be optimized.
+(defsubst msb--choose-menu (buffer function-info-vector max-buffer-name-length)
+  (unless (and (not msb-display-invisible-buffers-p)
+	       (msb-invisible-buffer-p buffer))
+    (condition-case nil
+	(save-excursion
+	  (set-buffer buffer)
+	  ;; Menu found. Add to this menu
+	  (mapc (function
+		 (lambda (function-info)
+		   (msb--add-to-menu buffer function-info max-buffer-name-length)))
+		(msb--collect function-info-vector)))
+      (error (unless msb--error
+	       (setq msb--error
+		     (format
+		      "Variable `msb-menu-cond': Error for buffer \"%s\"."
+		      (buffer-name buffer)))
+	       (error msb--error))))))
+
+;; Return (SORT-KEY TITLE . BUFFER-LIST) or nil if the
+;; buffer-list is empty.
+(defun msb--create-sort-item (function-info)
+  (let ((buffer-list (eval (aref function-info 0))))
+    (when buffer-list
+      (let ((sorter (aref function-info 5)) ;SORTER
+	    (sort-key (aref function-info 2))) ;MENU-SORT-KEY
+	(when sort-key
+	  (cons sort-key	
+		(cons (format (aref function-info 3) ;MENU-TITLE
+			      (length buffer-list))
+		      (cond
+		       ((null sorter)
+			buffer-list)
+		       ((eq sorter 't)
+			(nreverse buffer-list))
+		       (t
+			(sort buffer-list sorter))))))))))
+
+;; Returns a list on the form ((TITLE . BUFFER-LIST)) for
+;; the most recently used buffers.
+(defun msb--most-recently-used-menu (max-buffer-name-length)
+  (when (and msb-display-most-recently-used
+	     (or (not (numberp msb-display-most-recently-used))
+		 (> msb-display-most-recently-used 0)))
+    (let* ((max-in-menu
+	    (if (numberp msb-display-most-recently-used)
+		msb-display-most-recently-used
+	      msb-max-menu-items))
+
+	   (most-recently-used
+	    (loop with n = 0
+		  for buffer in (cdr (buffer-list))
+		  if (save-excursion
+		       (set-buffer buffer)
+		       (and (not (msb-invisible-buffer-p))
+			    (not (eq major-mode 'dired-mode))))
+		  collect (save-excursion
+			    (set-buffer buffer)
+			    (cons (funcall msb-item-handling-function
+					   buffer
+					   max-buffer-name-length)
+				  buffer))
+		  and do (incf n)
+		  until (and max-in-menu (>= n max-in-menu)))))
+      (cons (if (stringp msb-most-recently-used-title)
+		(format msb-most-recently-used-title
+			(length most-recently-used))
+	      (signal 'wrong-type-argument (list msb-most-recently-used-title)))
+	    most-recently-used))))
+
+(defun msb--create-buffer-menu-2 ()
+  (let ((max-buffer-name-length 0)
+	file-buffers
+	function-info-vector)
+    ;; Calculate the longest buffer name.
+    (mapc
+     (function
+      (lambda (buffer)
+	(if (or msb-display-invisible-buffers-p
+		(not (msb-invisible-buffer-p)))
+	    (setq max-buffer-name-length
+		  (max max-buffer-name-length
+		       (length (buffer-name buffer)))))))
+     (buffer-list))
+    ;; Make a list with elements of type
+    ;; (BUFFER-LIST-VARIABLE
+    ;;  CONDITION
+    ;;  MENU-SORT-KEY
+    ;;  MENU-TITLE
+    ;;  ITEM-HANDLER
+    ;;  SORTER)
+    ;; Uses "function-global" variables:
+    ;; function-info-vector
+    (setq function-info-vector
+	  (apply (function vector)
+		 (mapcar (function msb--create-function-info)
+			 msb-menu-cond)))
+    ;; Split the buffer-list into several lists; one list for each
+    ;; criteria. This is the most critical part with respect to time.
+    (mapc (function (lambda (buffer)
+		      (cond ((and msb-files-by-directory
+				  (buffer-file-name buffer))
+			     (push buffer file-buffers))
+			    (t
+			     (msb--choose-menu buffer
+					       function-info-vector
+					       max-buffer-name-length)))))
+	  (buffer-list))
+    (when file-buffers
+      (setq file-buffers
+	    (mapcar (function
+		     (lambda (buffer-list)
+		       (cons msb-files-by-directory-sort-key
+			     (cons (car buffer-list)
+				   (sort
+				    (mapcar (function
+					     (lambda (buffer)
+					       (cons (buffer-name buffer)
+						     buffer)))
+					    (cdr buffer-list))
+				    (function
+				     (lambda (item1 item2)
+				       (string< (car item1) (car item2)))))))))
+		     (msb--choose-file-menu file-buffers))))
+    ;; Now make the menu - a list of (TITLE . BUFFER-LIST)
+    (let* ((buffers (buffer-list))
+	   menu
+	   (most-recently-used
+	    (msb--most-recently-used-menu max-buffer-name-length))
+	   (others (append file-buffers
+			   (loop for elt
+			 across function-info-vector
+			 for value = (msb--create-sort-item elt)
+			 if value collect value))))
+      (setq menu
+	    (mapcar 'cdr		;Remove the SORT-KEY
+		    ;; Sort the menus - not the items.
+		    (msb--add-separators
+		    (sort
+		     ;; Get a list of (SORT-KEY TITLE . BUFFER-LIST)
+		     ;; Also sorts the items within the menus.
+		     (if (cdr most-recently-used)
+			 (cons
+			  ;; Add most recent used buffers
+			  (cons msb-most-recently-used-sort-key
+				most-recently-used)
+			  others)
+		       others)
+		     (function (lambda (elt1 elt2)
+				 (< (car elt1) (car elt2))))))))
+      ;; Now make it a keymap menu
+      (append
+       '(keymap "Select Buffer")
+       (msb--make-keymap-menu menu)
+       (when msb-separator-diff
+	 (list (list 'separator "---")))
+       (list (cons 'toggle 
+		   (cons
+		   (if msb-files-by-directory
+		       "*Files by type*"
+		     "*Files by directory*")
+		   'msb--toggle-menu-type)))))))
+
+(defun msb--create-buffer-menu  ()
+  (save-match-data
+    (save-excursion
+      (msb--create-buffer-menu-2))))
+
+;;;
+;;; Multi purpose function for selecting a buffer with the mouse.
+;;; 
+(defun msb--toggle-menu-type ()
+  (interactive)
+  (setq msb-files-by-directory (not msb-files-by-directory))
+  (menu-bar-update-buffers t))
+
+(defun mouse-select-buffer (event)
+  "Pop up several menus of buffers, for selection with the mouse.
+Returns the selected buffer or nil if no buffer is selected.
+
+The way the buffers are splitted is conveniently handled with the
+variable 'msb-menu-cond'."
+  ;; Popup the menu and return the selected buffer.
+  (when (or msb--error
+	    (not msb--last-buffer-menu)
+	    (not (fboundp 'frame-or-buffer-changed-p))
+	    (frame-or-buffer-changed-p))
+    (setq msb--error nil)
+    (setq msb--last-buffer-menu (msb--create-buffer-menu)))
+  (let ((position event))
+    (when (and (fboundp 'posn-x-y)
+	       (fboundp 'posn-window))
+      (let ((posX (car (posn-x-y (event-start event))))
+	    (posY (cdr (posn-x-y (event-start event))))
+	    (posWind (posn-window (event-start event)))
+	    name)
+	;; adjust position
+	(setq posX (- posX (funcall msb-horizontal-shift-function))
+	      position (list (list posX posY) posWind))))
+    (setq name (x-popup-menu position msb--last-buffer-menu))
+    ;; If toggle bring up the
+    (cond
+     ((eq (car name) 'toggle)
+	(msb--toggle-menu-type)
+	(mouse-select-buffer event))
+     ((and (numberp (car name))
+	   (null (cdr name)))
+      (let ((msb--last-buffer-menu (nthcdr 3 (assq (car name) msb--last-buffer-menu))))
+	(mouse-select-buffer event)))
+      ((and (stringp (car name))
+	   (null (cdr name)))
+      (cons nil name))
+      (t
+       name))))
+		    
+;; Add separators
+(defun msb--add-separators (sorted-list)
+  (cond
+   ((or (not msb-separator-diff)
+	(not (numberp msb-separator-diff)))
+    sorted-list)
+   (t
+    (let ((last-key nil))
+      (mapcan
+       (function
+	(lambda (item)
+	  (cond
+	   ((and msb-separator-diff
+		 last-key 
+		 (> (- (car item) last-key)
+		    msb-separator-diff))
+	    (setq last-key (car item))
+	    (list (cons last-key 'separator)
+		  item))
+	   (t
+	    (setq last-key (car item))
+	    (list item)))))
+       sorted-list)))))
+
+(defun msb--make-keymap-menu (raw-menu)
+  (let ((end (cons '(nil) 'menu-bar-select-buffer))
+	(mcount 0))
+    (mapcar
+     (function
+      (lambda (sub-menu)
+	(cond 
+	 ((eq 'separator sub-menu)
+	  (list 'separator "---"))
+	 (t
+	  (append (list (incf mcount) (car sub-menu)
+			'keymap (car sub-menu))
+		  (mapcar (function
+			   (lambda (item)
+			     (let ((string (car item))
+				   (buffer (cdr item)))
+			       (cons (buffer-name buffer)
+				     (cons string end)))))
+		   (cdr sub-menu)))))))
+     raw-menu)))
+
+(defun menu-bar-update-buffers (&optional arg)
+  ;; If user discards the Buffers item, play along.
+  (when (and (lookup-key (current-global-map) [menu-bar buffer])
+	     (or (not (fboundp 'frame-or-buffer-changed-p))
+		 (frame-or-buffer-changed-p)
+		 arg))
+    (let ((buffers (buffer-list))
+	  (frames (frame-list))
+	  buffers-menu frames-menu)
+      ;; If requested, list only the N most recently selected buffers.
+      (when (and (integerp buffers-menu-max-size)
+		 (> buffers-menu-max-size 1)
+		 (> (length buffers) buffers-menu-max-size))
+	(setcdr (nthcdr buffers-menu-max-size buffers) nil))
+      ;; Make the menu of buffers proper.
+      (setq msb--last-buffer-menu (msb--create-buffer-menu))
+      (setq buffers-menu msb--last-buffer-menu)
+      ;; Make a Frames menu if we have more than one frame.
+      (if (cdr frames)
+	  (setq frames-menu
+		(cons "Select Frame"
+		      (mapcar
+		       (function
+			(lambda (frame)
+			  (nconc
+			   (list frame
+				 (cdr (assq 'name
+					    (frame-parameters frame)))
+				 (cons nil nil))
+			   'menu-bar-select-frame)))
+		       frames))))
+      (when frames-menu
+	(setq frames-menu (cons 'keymap frames-menu)))
+      (define-key (current-global-map) [menu-bar buffer]
+	(cons "Buffers"
+	      (if (and buffers-menu frames-menu)
+		  (list 'keymap "Buffers and Frames"
+			(cons 'buffers (cons "Buffers" buffers-menu))
+			(cons 'frames (cons "Frames" frames-menu)))
+		(or buffers-menu frames-menu 'undefined)))))))
+
+(when (and (boundp 'menu-bar-update-hook)
+	   (not (fboundp 'frame-or-buffer-changed-p)))
+  (defvar msb--buffer-count 0)
+  (defun frame-or-buffer-changed-p ()
+    (let ((count (length (buffer-list))))
+      (when (/= count msb--buffer-count)
+        (setq msb--buffer-count count)
+        t))))
+
+(unless (or (not (boundp 'menu-bar-update-hook))
+	    (memq 'menu-bar-update-buffers menu-bar-update-hook))
+    (add-hook 'menu-bar-update-hook 'menu-bar-update-buffers))
+
+(and (fboundp 'mouse-buffer-menu)
+     (substitute-key-definition 'mouse-buffer-menu 'msb (current-global-map)))
+
+(provide 'msb)
+(eval-after-load 'msb (run-hooks 'msb-after-load-hooks))
+;;; msb.el ends here