(rmail-toggle-header): Redo previous change;

don't move point if possible.
(rmail-count-screen-lines): Add.

1 files changed, 58 insertions, 35 deletions

diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index b94f4657c6f..0f3063769a8 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -1780,42 +1780,65 @@ Otherwise, delete all header fields whose names match `rmail-ignored-headers'."
 With argument ARG, show the message header pruned if ARG is greater than zero;
 otherwise, show it in full."
   (interactive "P")
+  (let* ((buffer-read-only nil)
+         (pruned (rmail-msg-is-pruned))
+         (prune (if arg
+                    (> (prefix-numeric-value arg) 0)
+                  (not pruned))))
+    (if (eq pruned prune)
+        t
+      (rmail-maybe-set-message-counters)
+      (let ((at-point-min (= (point) (point-min)))
+            (all-headers-visible (= (window-start) (point-min)))
+            (on-header (save-excursion
+                         (and (not (search-backward "\n\n" nil t))
+                              (progn
+                                (end-of-line)
+                                (re-search-backward "^[-A-Za-z0-9]+:" nil t))
+                              (match-string 0))))
+            (old-screen-line (rmail-count-screen-lines (window-start) (point))))
+        (save-excursion
+      (narrow-to-region (rmail-msgbeg rmail-current-message) (point-max))
+      (if pruned
+          (progn (goto-char (point-min))
+                 (forward-line 1)
+                 (delete-char 1)
+                 (insert ?0)
+                 (forward-line 1)
+                 (let ((case-fold-search t))
+                   (while (looking-at "Summary-Line:\\|Mail-From:")
+                     (forward-line 1)))
+                 (insert "*** EOOH ***\n")
+                 (forward-char -1)
+                     (search-forward "\n*** EOOH ***\n")
+                     (narrow-to-region (point) (point-max)))
+            (rmail-reformat-message (point-min) (point-max))))
+        (cond (at-point-min
+               (goto-char (point-min)))
+              (on-header
+               (goto-char (point-min))
+               (search-forward "\n\n")
+               (or (re-search-backward (concat "^" (regexp-quote on-header)) nil t)
+                   (goto-char (point-min))))
+              (t
+               (recenter old-screen-line)
+               (if (and all-headers-visible
+                        (not (= (window-start) (point-min))))
+                   (let ((lines-offscreen (rmail-count-screen-lines
+                                           (point-min) (window-start))))
+                     (recenter (min (+ old-screen-line lines-offscreen)
+                                    ;; last line of window
+                                    (- (window-height) 2))))))))
+      (rmail-highlight-headers))))
+
+;; Lifted from repos-count-screen-lines.
+;; Return number of screen lines between START and END.
+(defun rmail-count-screen-lines (start end)
   (save-excursion
-    (let* ((buffer-read-only nil)
-           (pruned (rmail-msg-is-pruned))
-           (prune (if arg
-                      (> (prefix-numeric-value arg) 0)
-                    (not pruned))))
-      (if (eq pruned prune)
-          t
-        (rmail-maybe-set-message-counters)
-        (narrow-to-region (rmail-msgbeg rmail-current-message) (point-max))
-        (if pruned
-            (let (window-at-top)
-              (goto-char (point-min))
-              (forward-line 1)
-              (delete-char 1)
-              (insert ?0)
-              (forward-line 1)
-              (let ((case-fold-search t))
-                (while (looking-at "Summary-Line:\\|Mail-From:")
-                  (forward-line 1)))
-              (insert "*** EOOH ***\n")
-              (forward-char -1)
-              (search-forward "\n*** EOOH ***\n")
-              (forward-line -1)
-              (let ((temp (point)))
-                (when (search-forward "\n\n" nil t)
-                  (if (< (window-start) (point))
-                      (setq window-at-top t))
-                  (delete-region temp (point))))
-              (goto-char (point-min))
-              (search-forward "\n*** EOOH ***\n")
-              (if window-at-top
-                  (set-window-start (selected-window) (point) t))
-              (narrow-to-region (point) (point-max)))
-          (rmail-reformat-message (point-min) (point-max)))
-        (rmail-highlight-headers)))))
+    (save-restriction
+      (narrow-to-region start end)
+      (goto-char (point-min))
+      (vertical-motion (- (point-max) (point-min))))))
 
 ;;;; *** Rmail Attributes and Keywords ***