Use (featurep 'xemacs) everywhere.

(follow-mode): Use define-minor-mode.
(follow-mode-map): Move initialization into the declaration.
Use command remapping.
(follow-emacs-version-xemacs-p): Remove.
(follow-submit-feedback): Remove.

2 files changed, 229 insertions, 303 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 76881128585..b4c19727934 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,12 @@
 2006-04-26  Stefan Monnier  <monnier@iro.umontreal.ca>
 
+        * follow.el: Use (featurep 'xemacs) everywhere.
+        (follow-mode): Use define-minor-mode.
+        (follow-mode-map): Move initialization into the declaration.
+        Use command remapping.
+        (follow-emacs-version-xemacs-p): Remove.
+        (follow-submit-feedback): Remove.
+
         * allout.el (allout-layout, allout-passphrase-verifier-string)
         (allout-passphrase-hint-string): Tighten up a bit the safety predicate.
 
diff --git a/lisp/follow.el b/lisp/follow.el
index 1958c407664..27c37132f0a 100644
--- a/lisp/follow.el
+++ b/lisp/follow.el
@@ -7,7 +7,6 @@
 ;; Maintainer: FSF (Anders' email bounces, Sep 2005)
 ;; Created: 1995-05-25
 ;; Keywords: display, window, minor-mode, convenience
-;; Last Changed: 1999-11-17
 
 ;; This file is part of GNU Emacs.
 
@@ -46,14 +45,14 @@
 ;;   movement commands.
 ;;
 ;; Follow mode comes to its prime when a large screen and two
-;; side-by-side window are used. The user can, with the help of Follow
+;; side-by-side window are used.  The user can, with the help of Follow
 ;; mode, use two full-height windows as though they would have been
-;; one. Imagine yourself editing a large function, or section of text,
+;; one.  Imagine yourself editing a large function, or section of text,
 ;; and being able to use 144 lines instead of the normal 72... (your
 ;; mileage may vary).
 
 ;; To test this package, make sure `follow' is loaded, or will be
-;; autoloaded when activated (see below). Then do the following:
+;; autoloaded when activated (see below).  Then do the following:
 ;;
 ;; * Find your favorite file (preferably a long one).
 ;;
@@ -77,13 +76,13 @@
 ;;                  +----------+----------+
 ;;
 ;;   As you can see, the right-hand window starts at line 73, the line
-;;   immediately below the end of the left-hand window. As long as
+;;   immediately below the end of the left-hand window.  As long as
 ;;   `follow-mode' is active, the two windows will follow eachother!
 ;;
 ;; * Play around and enjoy! Scroll one window and watch the other.
-;;   Jump to the beginning or end. Press `Cursor down' at the last
-;;   line of the left-hand window. Enter new lines into the
-;;   text. Enter long lines spanning several lines, or several
+;;   Jump to the beginning or end.  Press `Cursor down' at the last
+;;   line of the left-hand window.  Enter new lines into the
+;;   text.  Enter long lines spanning several lines, or several
 ;;   windows.
 ;;
 ;; * Should you find `Follow' mode annoying, just type
@@ -146,7 +145,7 @@
 ;; Usage:
 ;;
 ;; To activate issue the command "M-x follow-mode"
-;; and press return. To deactivate, do it again.
+;; and press return.  To deactivate, do it again.
 ;;
 ;; The following is a list of commands useful when follow-mode is active.
 ;;
@@ -197,7 +196,7 @@
 ;;    in the same frame. (My apoligies to you who can't use frames.)
 ;;
 ;; 2) Bind `follow-mode' to key so you can turn it off whenever
-;;    you want to view two locations. Of course, `follow' mode can
+;;    you want to view two locations.  Of course, `follow' mode can
 ;;    be reactivated by hitting the same key again.
 ;;
 ;;    Example from my ~/.emacs:
@@ -208,7 +207,7 @@
 ;;
 ;; In an ideal world, follow mode would have been implemented in the
 ;; kernel of the display routines, making sure that the windows (using
-;; follow mode) ALWAYS are aligned. On planet earth, however, we must
+;; follow mode) ALWAYS are aligned.  On planet earth, however, we must
 ;; accept a solution where we ALMOST ALWAYS can make sure that the
 ;; windows are aligned.
 ;;
@@ -222,7 +221,7 @@
 ;;
 ;; Note that only the selected window is checked, for the reason of
 ;; efficiency and code complexity. (I.e. it is possible to make a
-;; non-selected windows unaligned. It will, however, pop right back
+;; non-selected windows unaligned.  It will, however, pop right back
 ;; when it is selected.)
 
 ;;}}}
@@ -259,7 +258,7 @@
 (eval-when-compile
   (if (or (featurep 'bytecomp)
           (featurep 'byte-compile))
-      (cond ((string-match "XEmacs" emacs-version)
+      (cond ((featurep 'xemacs)
              ;; Make XEmacs shut up!  I'm using standard Emacs
              ;; functions, they are NOT obsolete!
              (if (eq (get 'force-mode-line-update 'byte-compile)
@@ -278,176 +277,44 @@
   :group 'windows
   :group 'convenience)
 
-(defvar follow-mode nil
-  "Variable indicating if Follow mode is active.")
-
 (defcustom follow-mode-hook nil
-  "*Hooks to run when follow-mode is turned on."
+  "Hooks to run when follow-mode is turned on."
   :type 'hook
   :group 'follow)
 
 (defcustom follow-mode-off-hook nil
-  "*Hooks to run when follow-mode is turned off."
+  "Hooks to run when follow-mode is turned off."
   :type 'hook
   :group 'follow)
 
-(defvar follow-mode-map nil
-  "*Minor mode keymap for Follow mode.")
 
-(defcustom follow-mode-line-text " Follow"
-  "*Text shown in the mode line when Follow mode is active.
-Defaults to \" Follow\".  Examples of other values
-are \" Fw\", or simply \"\"."
-  :type 'string
-  :group 'follow)
+;;{{{ Keymap/Menu
 
-(defcustom follow-auto nil
-  "*Non-nil activates Follow mode whenever a file is loaded."
-  :type 'boolean
-  :group 'follow)
+;; Define keys for the follow-mode minor mode map and replace some
+;; functions in the global map.  All `follow' mode special functions
+;; can be found on (the somewhat cumbersome) "C-c . <key>"
+;; (Control-C dot <key>). (As of Emacs 19.29 the keys
+;; C-c <punctuation character> are reserved for minor modes.)
+;;
+;; To change the prefix, redefine `follow-mode-prefix' before
+;; `follow' is loaded, or see the section on `follow-mode-hook'
+;; above for an example of how to bind the keys the way you like.
+;;
+;; Please note that the keymap is defined the first time this file is
+;; loaded.  Also note that the only legal way to manipulate the
+;; keymap is to use `define-key'.  Don't change it using `setq' or
+;; similar!
 
 (defcustom follow-mode-prefix "\C-c."
-  "*Prefix key to use for follow commands in Follow mode.
+  "Prefix key to use for follow commands in Follow mode.
 The value of this variable is checked as part of loading Follow mode.
 After that, changing the prefix key requires manipulating keymaps."
   :type 'string
   :group 'follow)
 
-(defcustom follow-intercept-processes
-  (fboundp 'start-process)
-  "*When non-nil, Follow Mode will monitor process output."
-  :type 'boolean
-  :group 'follow)
-
-(defvar follow-emacs-version-xemacs-p
-  (string-match "XEmacs" emacs-version)
-  "Non-nil when running under XEmacs.")
-
-(defvar follow-avoid-tail-recenter-p
-  (not follow-emacs-version-xemacs-p)
-  "*When non-nil, patch emacs so that tail windows won't be recentered.
-
-A \"tail window\" is a window that displays only the end of
-the buffer.  Normally it is practical for the user that empty
-windows are recentered automatically.  However, when using
-Follow Mode it breaks the display when the end is displayed
-in a window \"above\" the last window.  This is for
-example the case when displaying a short page in info.
-
-Must be set before Follow Mode is loaded.
-
-Please note that it is not possible to fully prevent Emacs from
-recentering empty windows.  Please report if you find a repeatable
-situation in which Emacs recenters empty windows.
-
-XEmacs, as of 19.12, does not recenter windows, good!")
-
-(defvar follow-cache-command-list
-  '(next-line previous-line forward-char backward-char)
-  "List of commands that don't require recalculation.
-
-In order to be able to use the cache, a command should not change the
-contents of the buffer, nor should it change selected window or current
-buffer.
-
-The commands in this list are checked at load time.
-
-To mark other commands as suitable for caching, set the symbol
-property `follow-mode-use-cache' to non-nil.")
-
-(defvar follow-debug nil
-  "*Non-nil when debugging Follow mode.")
-
-
-;; Internal variables:
-
-(defvar follow-internal-force-redisplay nil
-  "True when Follow mode should redisplay the windows.")
-
-(defvar follow-process-filter-alist '()
-  "The original filters for processes intercepted by Follow mode.")
-
-(defvar follow-active-menu nil
-  "The menu visible when Follow mode is active.")
-
-(defvar follow-deactive-menu nil
-  "The menu visible when Follow mode is deactivated.")
-
-(defvar follow-inside-post-command-hook nil
-  "Non-nil when inside Follow modes `post-command-hook'.
-Used by `follow-window-size-change'.")
-
-(defvar follow-windows-start-end-cache nil
-  "Cache used by `follow-window-start-end'.")
-
-;;}}}
-;;{{{ Bug report
-
-(eval-when-compile (require 'reporter))
-
-(defun follow-submit-feedback ()
-  "Submit feedback on Follow mode to the author: andersl@andersl.com"
-  (interactive)
-  (require 'reporter)
-  (and (y-or-n-p "Do you really want to submit a report on Follow mode? ")
-       (reporter-submit-bug-report
-        "Anders Lindgren <andersl@andersl.com>"
-        "follow.el"
-        '(post-command-hook
-          pre-command-hook
-          window-size-change-functions
-          window-scroll-functions
-          follow-mode-hook
-          follow-mode-off-hook
-          follow-auto
-          follow-intercept-processes
-          follow-avoid-tail-recenter-p
-          follow-process-filter-alist)
-        nil
-        nil
-        (concat
-         "Hi Anders!\n\n"
-         "(I have read the section on how to report bugs in the "
-         "Emacs manual.)\n\n"
-         "Even though I know you are busy, I thought you might "
-         "want to know...\n\n"))))
-
-;;}}}
-;;{{{ Debug messages
-
-;; This inline function must be as small as possible!
-;; Maybe we should define a macro that expands to nil if
-;; the variable is not set.
-
-(defsubst follow-debug-message (&rest args)
-  "Like message, but only active when `follow-debug' is non-nil."
-  (if (and (boundp 'follow-debug) follow-debug)
-      (apply 'message args)))
-
-;;}}}
-
-;;{{{ Keymap/Menu
-
-;;; Define keys for the follow-mode minor mode map and replace some
-;;; functions in the global map.  All `follow' mode special functions
-;;; can be found on (the somewhat cumbersome) "C-c . <key>"
-;;; (Control-C dot <key>). (As of Emacs 19.29 the keys
-;;; C-c <punctuation character> are reserved for minor modes.)
-;;;
-;;; To change the prefix, redefine `follow-mode-prefix' before
-;;; `follow' is loaded, or see the section on `follow-mode-hook'
-;;; above for an example of how to bind the keys the way you like.
-;;;
-;;; Please note that the keymap is defined the first time this file is
-;;; loaded.  Also note that the only legal way to manipulate the
-;;; keymap is to use `define-key'.  Don't change it using `setq' or
-;;; similar!
-
-
-(if follow-mode-map
-    nil
-  (setq follow-mode-map (make-sparse-keymap))
-  (let ((map (make-sparse-keymap)))
+(defvar follow-mode-map
+  (let ((mainmap (make-sparse-keymap))
+        (map (make-sparse-keymap)))
     (define-key map "\C-v"      'follow-scroll-up)
     (define-key map "\M-v"      'follow-scroll-down)
     (define-key map "v"         'follow-scroll-down)
@@ -460,38 +327,26 @@ Used by `follow-window-size-change'.")
     (define-key map "n"         'follow-next-window)
     (define-key map "p"         'follow-previous-window)
 
-    (define-key follow-mode-map follow-mode-prefix map)
+    (define-key mainmap follow-mode-prefix map)
 
     ;; Replace the standard `end-of-buffer', when in Follow Mode.  (I
     ;; don't see the point in trying to replace every function that
     ;; could be enhanced in Follow mode.  End-of-buffer is a special
     ;; case since it is very simple to define and it greatly enhances
     ;; the look and feel of Follow mode.)
-    ;;
-    ;; (The function `substitute-key-definition' does not work
-    ;; in all versions of Emacs.)
-    (mapcar
-     (function
-      (lambda (pair)
-        (let ((old (car pair))
-              (new (cdr pair)))
-          (mapcar (function (lambda (key)
-                              (define-key follow-mode-map key new)))
-                  (where-is-internal old global-map)))))
-     '((end-of-buffer      . follow-end-of-buffer)
-       (fkey-end-of-buffer . follow-end-of-buffer)))
+    (define-key mainmap [remap end-of-buffer] 'follow-end-of-buffer)
 
-    ;;;
-    ;;; The menu.
-    ;;;
+    ;;
+    ;; The menu.
+    ;;
 
-    (if (not follow-emacs-version-xemacs-p)
+    (if (not (featurep 'xemacs))
 
         ;;
         ;; Emacs
         ;;
         (let ((menumap (funcall (symbol-function 'make-sparse-keymap)
-                        "Follow"))
+                                "Follow"))
               (count 0)
               id)
           (mapcar
@@ -516,16 +371,16 @@ Used by `follow-window-size-change'.")
              ("First Window"       . follow-first-window)
              ("--")
              ("Switch To Buffer (all windows)"
-                                   . follow-switch-to-buffer-all)
+              . follow-switch-to-buffer-all)
              ("Switch To Buffer"   . follow-switch-to-buffer)
              ("--")
              ("Delete Other Windows and Split"
-                                   . follow-delete-other-windows-and-split)
+              . follow-delete-other-windows-and-split)
              ("--")
              ("Scroll Down"        . follow-scroll-down)
              ("Scroll Up"          . follow-scroll-up)))
 
-          ;; If there is a `tools' meny, we use it. However, we can't add a
+          ;; If there is a `tools' menu, we use it.  However, we can't add a
           ;; minor-mode specific item to it (it's broken), so we make the
           ;; contents ghosted when not in use, and add ourselves to the
           ;; global map.  If no `tools' menu is present, just make a
@@ -546,7 +401,7 @@ Used by `follow-window-size-change'.")
                   (if last
                       (progn
                         (funcall (symbol-function 'define-key-after)
-                                  tools-map [separator-follow] '("--") last)
+                                 tools-map [separator-follow] '("--") last)
                         (funcall (symbol-function 'define-key-after)
                                  tools-map [follow] (cons "Follow" menumap)
                                  'separator-follow))
@@ -555,7 +410,7 @@ Used by `follow-window-size-change'.")
                     (define-key (current-global-map) [menu-bar tools follow]
                       (cons "Follow" menumap))))
               ;; No tools menu, add "Follow" to the menubar.
-              (define-key follow-mode-map [menu-bar follow]
+              (define-key mainmap [menu-bar follow]
                 (cons "Follow" menumap)))))
 
       ;;
@@ -593,21 +448,103 @@ Used by `follow-window-size-change'.")
       (defun follow-menu-filter (menu)
         (if follow-mode
             menu
-          '(["Activate          " follow-mode t]))))))
+          '(["Activate          " follow-mode t]))))
+    
+    mainmap)
+  "Minor mode keymap for Follow mode.")
 
+;;}}}
 
-;;; Register the follow mode keymap.
-(or (assq 'follow-mode minor-mode-map-alist)
-    (setq minor-mode-map-alist
-          (cons (cons 'follow-mode follow-mode-map) minor-mode-map-alist)))
+(defcustom follow-mode-line-text " Follow"
+  "Text shown in the mode line when Follow mode is active.
+Defaults to \" Follow\".  Examples of other values
+are \" Fw\", or simply \"\"."
+  :type 'string
+  :group 'follow)
+
+(defcustom follow-auto nil
+  "Non-nil activates Follow mode whenever a file is loaded."
+  :type 'boolean
+  :group 'follow)
+
+(defcustom follow-intercept-processes (fboundp 'start-process)
+  "When non-nil, Follow Mode will monitor process output."
+  :type 'boolean
+  :group 'follow)
+
+(defvar follow-avoid-tail-recenter-p (not (featurep 'xemacs))
+  "*When non-nil, patch emacs so that tail windows won't be recentered.
+
+A \"tail window\" is a window that displays only the end of
+the buffer.  Normally it is practical for the user that empty
+windows are recentered automatically.  However, when using
+Follow Mode it breaks the display when the end is displayed
+in a window \"above\" the last window.  This is for
+example the case when displaying a short page in info.
+
+Must be set before Follow Mode is loaded.
+
+Please note that it is not possible to fully prevent Emacs from
+recentering empty windows.  Please report if you find a repeatable
+situation in which Emacs recenters empty windows.
+
+XEmacs, as of 19.12, does not recenter windows, good!")
+
+(defvar follow-cache-command-list
+  '(next-line previous-line forward-char backward-char)
+  "List of commands that don't require recalculation.
+
+In order to be able to use the cache, a command should not change the
+contents of the buffer, nor should it change selected window or current
+buffer.
+
+The commands in this list are checked at load time.
+
+To mark other commands as suitable for caching, set the symbol
+property `follow-mode-use-cache' to non-nil.")
+
+(defvar follow-debug nil
+  "*Non-nil when debugging Follow mode.")
+
+
+;; Internal variables:
+
+(defvar follow-internal-force-redisplay nil
+  "True when Follow mode should redisplay the windows.")
+
+(defvar follow-process-filter-alist '()
+  "The original filters for processes intercepted by Follow mode.")
+
+(defvar follow-active-menu nil
+  "The menu visible when Follow mode is active.")
+
+(defvar follow-deactive-menu nil
+  "The menu visible when Follow mode is deactivated.")
+
+(defvar follow-inside-post-command-hook nil
+  "Non-nil when inside Follow modes `post-command-hook'.
+Used by `follow-window-size-change'.")
+
+(defvar follow-windows-start-end-cache nil
+  "Cache used by `follow-window-start-end'.")
+
+;;}}}
+;;{{{ Debug messages
+
+;; This inline function must be as small as possible!
+;; Maybe we should define a macro that expands to nil if
+;; the variable is not set.
+
+(defsubst follow-debug-message (&rest args)
+  "Like message, but only active when `follow-debug' is non-nil."
+  (if (and (boundp 'follow-debug) follow-debug)
+      (apply 'message args)))
 
 ;;}}}
 ;;{{{ Cache
 
-(let ((cmds follow-cache-command-list))
-  (while cmds
-    (put (car cmds) 'follow-mode-use-cache t)
-    (setq cmds (cdr cmds))))
+(dolist (cmd follow-cache-command-list)
+  (put cmd 'follow-mode-use-cache t))
 
 ;;}}}
 
@@ -615,20 +552,20 @@ Used by `follow-window-size-change'.")
 
 ;;;###autoload
 (defun turn-on-follow-mode ()
-  "Turn on Follow mode. Please see the function `follow-mode'."
+  "Turn on Follow mode.  Please see the function `follow-mode'."
   (interactive)
   (follow-mode 1))
 
 
 ;;;###autoload
 (defun turn-off-follow-mode ()
-  "Turn off Follow mode. Please see the function `follow-mode'."
+  "Turn off Follow mode.  Please see the function `follow-mode'."
   (interactive)
   (follow-mode -1))
 
-
+(put 'follow-mode 'permanent-local t)
 ;;;###autoload
-(defun follow-mode (arg)
+(define-minor-mode follow-mode
   "Minor mode that combines windows into one tall virtual window.
 
 The feeling of a \"virtual window\" has been accomplished by the use
@@ -665,39 +602,21 @@ is called.  When turned off, `follow-mode-off-hook' is called.
 
 Keys specific to Follow mode:
 \\{follow-mode-map}"
-  (interactive "P")
-  (make-local-variable 'follow-mode)
-  (put 'follow-mode 'permanent-local t)
-  (let ((follow-mode-orig follow-mode))
-    (setq follow-mode
-          (if (null arg)
-              (not follow-mode)
-            (> (prefix-numeric-value arg) 0)))
-    (if (and follow-mode follow-intercept-processes)
-        (follow-intercept-process-output))
-    (cond ((and follow-mode (not follow-mode-orig)) ; On
-           ;; XEmacs: If this is non-nil, the window will scroll before
-           ;; the point will have a chance to get into the next window.
-           (if (boundp 'scroll-on-clipped-lines)
-               (set 'scroll-on-clipped-lines nil))
-           (force-mode-line-update)
-           (add-hook 'post-command-hook 'follow-post-command-hook t)
-           (run-hooks 'follow-mode-hook))
-
-          ((and (not follow-mode) follow-mode-orig) ; Off
-           (force-mode-line-update)
-           (run-hooks 'follow-mode-off-hook)))))
-
-
-;; Register follow-mode as a minor mode.
-
-(if (fboundp 'add-minor-mode)
-    ;; XEmacs
-    (funcall (symbol-function 'add-minor-mode)
-             'follow-mode 'follow-mode-line-text)
-  (or (assq 'follow-mode minor-mode-alist)
-      (setq minor-mode-alist
-            (cons '(follow-mode follow-mode-line-text) minor-mode-alist))))
+  :keymap follow-mode-map
+  (if (and follow-mode follow-intercept-processes)
+      (follow-intercept-process-output))
+  (cond (follow-mode ; On
+         ;; XEmacs: If this is non-nil, the window will scroll before
+         ;; the point will have a chance to get into the next window.
+         (if (boundp 'scroll-on-clipped-lines)
+             (setq scroll-on-clipped-lines nil))
+         (force-mode-line-update)
+         (add-hook 'post-command-hook 'follow-post-command-hook t)
+         (run-hooks 'follow-mode-hook))
+
+        ((not follow-mode) ; Off
+         (force-mode-line-update)
+         (run-hooks 'follow-mode-off-hook))))
 
 ;;}}}
 ;;{{{ Find file hook
@@ -1033,7 +952,7 @@ window, normally is the end plus one.
 If WIN is nil, the selected window is used.
 
 Returns (end-pos end-of-buffer-p)"
-  (if follow-emacs-version-xemacs-p
+  (if (featurep 'xemacs)
       ;; XEmacs can calculate the end of the window by using
       ;; the 'guarantee options. GOOD!
       (let ((end (window-end win t)))
@@ -1511,7 +1430,7 @@ non-first windows in Follow Mode."
 ;;}}}
 ;;{{{ Post Command Hook
 
-;;; The magic little box. This function is called after every command.
+;; The magic little box. This function is called after every command.
 
 ;; This is not as complicated as it seems. It is simply a list of common
 ;; display situations and the actions to take, plus commands for redrawing
@@ -1735,17 +1654,17 @@ non-first windows in Follow Mode."
 
 ;;;; Scroll-bar support code.
 
-;;; Why is it needed? Well, if the selected window is in follow mode,
-;;; all its follower stick to it blindly. If one of them is scrolled,
-;;; it immediately returns to the original position when the mouse is
-;;; released. If the selected window is not a follower of the dragged
-;;; window the windows will be unaligned.
+;; Why is it needed? Well, if the selected window is in follow mode,
+;; all its follower stick to it blindly. If one of them is scrolled,
+;; it immediately returns to the original position when the mouse is
+;; released. If the selected window is not a follower of the dragged
+;; window the windows will be unaligned.
 
-;;; The advices doesn't get compiled. Aestetically, this might be a
-;;; problem but in practical life it isn't.
+;; The advices doesn't get compiled. Aestetically, this might be a
+;; problem but in practical life it isn't.
 
-;;; Discussion: Now when the other windows in the chain follow the
-;;; dragged, should we really select it?
+;; Discussion: Now when the other windows in the chain follow the
+;; dragged, should we really select it?
 
 (cond ((fboundp 'scroll-bar-drag)
        ;;;
@@ -1851,29 +1770,29 @@ WINDOW can be an object or a window."
 ;;}}}
 ;;{{{ Process output
 
-;;; The following sections installs a spy that listens to process
-;;; output and tries to reposition the windows whose buffers are in
-;;; Follow mode.  We play safe as much as possible...
-;;;
-;;; When follow-mode is activated all active processes are
-;;; intercepted.  All new processes that change their filter function
-;;; using `set-process-filter' are also intercepted.  The reason is
-;;; that a process can cause a redisplay recentering "tail" windows.
-;;; Note that it doesn't hurt to spy on more processes than needed.
-;;;
-;;; Technically, we set the process filter to `follow-generic-filter'.
-;;; The original filter is stored in `follow-process-filter-alist'.
-;;; Our generic filter calls the original filter, or inserts the
-;;; output into the buffer, if the buffer originally didn't have an
-;;; output filter.  It also makes sure that the windows connected to
-;;; the buffer are aligned.
-;;;
-;;; Discussion: How do we find processes that don't call
-;;; `set-process-filter'?  (How often are processes created in a
-;;; buffer after Follow mode are activated?)
-;;;
-;;; Discussion: Should we also advice `process-filter' to make our
-;;; filter invisible to others?
+;; The following sections installs a spy that listens to process
+;; output and tries to reposition the windows whose buffers are in
+;; Follow mode.  We play safe as much as possible...
+;;
+;; When follow-mode is activated all active processes are
+;; intercepted.  All new processes that change their filter function
+;; using `set-process-filter' are also intercepted.  The reason is
+;; that a process can cause a redisplay recentering "tail" windows.
+;; Note that it doesn't hurt to spy on more processes than needed.
+;;
+;; Technically, we set the process filter to `follow-generic-filter'.
+;; The original filter is stored in `follow-process-filter-alist'.
+;; Our generic filter calls the original filter, or inserts the
+;; output into the buffer, if the buffer originally didn't have an
+;; output filter.  It also makes sure that the windows connected to
+;; the buffer are aligned.
+;;
+;; Discussion: How do we find processes that don't call
+;; `set-process-filter'?  (How often are processes created in a
+;; buffer after Follow mode are activated?)
+;;
+;; Discussion: Should we also advice `process-filter' to make our
+;; filter invisible to others?
 
 ;;{{{ Advice for `set-process-filter'
 
@@ -1980,7 +1899,7 @@ connected to processes.
 
 The only reason to call this function is if the Follow mode spy filter
 would interfere with some other package.  If this happens, please
-report this using the `follow-submit-feedback' function."
+report this using the `report-emacs-bug' function."
   (interactive)
   (follow-tidy-process-filter-alist)
   (let ((list (process-list)))
@@ -1999,12 +1918,12 @@ report this using the `follow-submit-feedback' function."
 ;;}}}
 ;;{{{ The filter
 
-;;; The following section is a naive method to make buffers with
-;;; process output to work with Follow mode. Whenever the start of the
-;;; window displaying the buffer is moved, we moves it back to its
-;;; original position and try to select a new window.  (If we fail,
-;;; the normal redisplay functions of Emacs will scroll it right
-;;; back!)
+;; The following section is a naive method to make buffers with
+;; process output to work with Follow mode. Whenever the start of the
+;; window displaying the buffer is moved, we moves it back to its
+;; original position and try to select a new window.  (If we fail,
+;; the normal redisplay functions of Emacs will scroll it right
+;; back!)
 
 (defun follow-generic-filter (proc output)
   "Process output filter for process connected to buffers in Follow mode."
@@ -2219,7 +2138,7 @@ report this using the `follow-submit-feedback' function."
 ;; unless we are in `slow-search-mode', i.e. only a few lines
 ;; of text is visible.
 
-(if follow-emacs-version-xemacs-p
+(if (featurep 'xemacs)
     (defadvice isearch-done (before follow-isearch-done activate)
       (if (and (boundp 'follow-mode)
                follow-mode
@@ -2235,28 +2154,28 @@ report this using the `follow-submit-feedback' function."
 ;;}}}
 ;;{{{ Tail window handling
 
-;;; In Emacs (not XEmacs) windows showing nothing are sometimes
-;;; recentered.  When in Follow Mode, this is not desireable for
-;;; non-first windows in the window chain.  This section tries to
-;;; make the windows stay where they should be.
-;;;
-;;; If the display is updated, all windows starting at (point-max) are
-;;; going to be recentered at the next redisplay, unless we do a
-;;; read-and-write cycle to update the `force' flag inside the windows.
-;;;
-;;; In 19.30, a new varible `window-scroll-functions' is called every
-;;; time a window is recentered.  It is not perfect for our situation,
-;;; since when it is called for a tail window, it is to late.  However,
-;;; if it is called for another window, we can try to update our
-;;; windows.
-;;;
-;;; By patching `sit-for' we can make sure that to catch all explicit
-;;; updates initiated by lisp programs.  Internal calls, on the other
-;;; hand, are not handled.
-;;;
-;;; Please note that the function `follow-avoid-tail-recenter' is also
-;;; called from other places, e.g. `post-command-hook' and
-;;; `post-command-idle-hook'.
+;; In Emacs (not XEmacs) windows showing nothing are sometimes
+;; recentered.  When in Follow Mode, this is not desireable for
+;; non-first windows in the window chain.  This section tries to
+;; make the windows stay where they should be.
+;;
+;; If the display is updated, all windows starting at (point-max) are
+;; going to be recentered at the next redisplay, unless we do a
+;; read-and-write cycle to update the `force' flag inside the windows.
+;;
+;; In 19.30, a new varible `window-scroll-functions' is called every
+;; time a window is recentered.  It is not perfect for our situation,
+;; since when it is called for a tail window, it is to late.  However,
+;; if it is called for another window, we can try to update our
+;; windows.
+;;
+;; By patching `sit-for' we can make sure that to catch all explicit
+;; updates initiated by lisp programs.  Internal calls, on the other
+;; hand, are not handled.
+;;
+;; Please note that the function `follow-avoid-tail-recenter' is also
+;; called from other places, e.g. `post-command-hook' and
+;; `post-command-idle-hook'.
 
 ;; If this function is called it is too late for this window, but
 ;; we might save other windows from being recentered.
@@ -2328,9 +2247,9 @@ This prevents `mouse-drag-region' from messing things up."
 
 ;;{{{ The end
 
-;;;
-;;; We're done!
-;;;
+;;
+;; We're done!
+;;
 
 (provide 'follow)