Re: [PATCH] Save and restore point explicitly in `notmuch-wash-toggle-invisible-action'.

[Carl Worth <cworth@cworth.org>]

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On Tue, 24 May 2011 18:43:41 -0400, Austin Clements <amdragon@mit.edu> wrote:
> Saving point this way is a bit dangerous, though.  For example, if
> you're near the end of the buffer and shorten the label, attempting to
> restore the point could result in an error (or, a more benign example:
> the cursor could wind up outside the label so pressing RET repeatedly
> won't toggle it).
> 
> Unfortunately, I don't know of a clean solution to this, but I think I
> would rather the cursor move, but stay within the label (probably
> moving to the beginning), than have problems like the above.

Here's my fix. Let me know what you think.

-Carl


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From a32e02bf0d2b57d51695f7d4ea6cdda9acb21322 Mon Sep 17 00:00:00 2001
From: Carl Worth <cworth@cworth.org>
Date: Mon, 23 May 2011 19:29:46 +0400
Subject: [PATCH] Carefully preverse point when changing button text in
 `notmuch-wash-toggle-invisible-action'.

Previously, save-excursion was used to attempt to save the point, but
this was unreliable since the region containing the marker saved by
save-excursion was deleted. Instead, we save an integer position
indicating the offset of point within the old button. Then, we restore
point to the same offset within the new button, (but cap the offset to
avoid leaving the button entirely).
---
 emacs/notmuch-wash.el |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/emacs/notmuch-wash.el b/emacs/notmuch-wash.el
index 8455eee..3dceb8b 100644
--- a/emacs/notmuch-wash.el
+++ b/emacs/notmuch-wash.el
@@ -82,13 +82,14 @@ collapse the remaining lines into a button.")
   (let* ((new-start (button-start cite-button))
 	 (overlay (button-get cite-button 'overlay))
 	 (button-label (notmuch-wash-button-label overlay))
+	 (button-offset (- (point) new-start))
 	 (inhibit-read-only t))
-    (save-excursion
-      (goto-char new-start)
-      (insert button-label)
-      (let ((old-end (button-end cite-button)))
-	(move-overlay cite-button new-start (point))
-	(delete-region (point) old-end))))
+    (goto-char new-start)
+    (insert button-label)
+    (let ((old-end (button-end cite-button)))
+      (move-overlay cite-button new-start (point))
+      (delete-region (point) old-end))
+    (goto-char (min (button-end cite-button) (+ new-start button-offset))))
   (force-window-update)
   (redisplay t))
 
-- 
1.7.5.1


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