Preserve visual position when refreshing

Both for question list and question mode.

2 files changed, 17 insertions, 12 deletions

diff --git a/sx-question-list.el b/sx-question-list.el
index 2965ede..bb49b54 100644
--- a/sx-question-list.el
+++ b/sx-question-list.el
@@ -371,19 +371,21 @@ a new list before redisplaying."
   (setq sx-question-list--unread-count 0)
   (unless no-update
     (setq sx-question-list--pages-so-far 1))
-  (let ((question-list
-         (or (and no-update sx-question-list--dataset)
-             (and (functionp sx-question-list--refresh-function)
-                  (funcall sx-question-list--refresh-function))
-             (and (functionp sx-question-list--next-page-function)
-                  (funcall sx-question-list--next-page-function 1))
-             sx-question-list--dataset)))
+  (cl-letf ((question-list
+             (or (and no-update sx-question-list--dataset)
+                 (and (functionp sx-question-list--refresh-function)
+                      (funcall sx-question-list--refresh-function))
+                 (and (functionp sx-question-list--next-page-function)
+                      (funcall sx-question-list--next-page-function 1))
+                 sx-question-list--dataset))
+            ;; Preserve window positioning.
+            ((window-start)))
     (setq sx-question-list--dataset question-list)
     ;; Print the result.
     (setq tabulated-list-entries
           (mapcar sx-question-list--print-function
-                  (cl-remove-if #'sx-question--hidden-p question-list))))
-  (when redisplay (tabulated-list-print 'remember)))
+                  (cl-remove-if #'sx-question--hidden-p question-list)))
+    (when redisplay (tabulated-list-print 'remember))))
 
 (defcustom sx-question-list-ago-string " ago"
   "String appended to descriptions of the time since something happened.
diff --git a/sx-question-mode.el b/sx-question-mode.el
index 70b8866..c90e3e1 100644
--- a/sx-question-mode.el
+++ b/sx-question-mode.el
@@ -595,15 +595,18 @@ With non-nil prefix argument NO-UPDATE, just redisplay, don't
 query the api."
   (interactive "P")
   (sx-question-mode--ensure-mode)
-  (let ((point (point)))
+  (let ((point (point))
+        (line (count-screen-lines
+               (window-start) (point))))
     (sx-question-mode--erase-and-print-question
      (if no-update
          sx-question-mode--data
        (sx-assoc-let sx-question-mode--data
          (sx-question-get-question .site .question_id))))
     (goto-char point)
-    (when (get-buffer-window (current-buffer))
-      (recenter))))
+    (when (equal (selected-window)
+                 (get-buffer-window (current-buffer)))
+      (recenter line))))
 
 (defun sx-question-mode--ensure-mode ()
   "Ensures we are in question mode, erroring otherwise."