I have a number of macros for browsing source code for many emacs versions. I wrote this in 2009 and it's been solid until upgrading to U18.04. I know it worked in U16.04:

(defun get-file-from-buffer-other-window ()
  "Load a file into another window referenced by the string on the current line"

  ;; get the filename and lineno
  (setq vals (get-fileline))
  (print vals)

  ;; load the filename into the next window and goto linenumber
  (switch-to-buffer-other-window (find-file-noselect (nth 0 vals)))
  (goto-line (nth 1 vals))

I split a frame and have a file list in one window, select a file from the list, which loads it into a buffer and loads the buffer in the other window. Two windows in the frame.

In the new version 25.2.2, the default behavior changed. Now selecting a file opens a NEW window in the frame. Look at five files (key bind to f8) and five new windows are created. I traced the issue to the windows.el display-buffer macro. There is a tuning action named display-buffer-base-action. I try changing the behavior, specifically to display-buffer-reuse-window but cannot get it to recreate the behavior emacs has defaulted since I wrote it in 2009. WTF?

Any ideas? I'm sure it is something to do with display-buffer-reuse-window and this documentation. https://www.gnu.org/software/emacs/manual/html_node/elisp/Precedence-of-Action-Functions.html


  • Incidentally, the primary macro to load the file/buffer into the existing window works fine using switch-to-buffer. But then I lose the source file list. I have additional macros that search the source file list for regex patterns and then I can click on the file/lines that match the pattern. Much more helpful to search a large code base than tags.
    – dturvene
    Apr 26, 2019 at 19:11
  • I'm testing with the following macros in a frame with two windows. foo should be loaded in a new window in the frame and bar should be loaded into the same window - at least that's the way it used to work.... <br \> (switch-to-buffer-other-window (get-buffer-create "foo")) (switch-to-buffer-other-window (get-buffer-create "bar"))
    – dturvene
    Apr 26, 2019 at 19:52

1 Answer 1


As with all my emacs work, I take it for granted until something doesn't work and then I need to dig into it. It's a tool but you need to sharpen it to cut bait...

Not the best solution but here's what works for me. I took it from:

How to force completions buffer to appear in a side window?

(defun display-on-side (buffer &optional not-this-window frame)
  (let* ((window (or (minibuffer-selected-window)
         (display-buffer-function nil)
         (pop-up-windows nil))
    (with-selected-window (or window (error "display-on-side"))
      (when (one-window-p t)
      (display-buffer buffer not-this-window frame))))

(setq display-buffer-function 'display-on-side)

;; unit test, should open in the same side window.
(display-buffer (get-buffer-create "*foo*"))
(display-buffer (get-buffer-create "*bar*"))

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.