*Help* windows appear to have a special behavior. For example, if I open a help window using C-h f butterfly, the window will open in a separate half-page buffer. If I use the help feature again C-h f tetris, the same help-mode buffer will be reused to display the documentation for tetris. Is there a way to replicate this behavior for other windows? For example, I would like EWW windows to have a behavior similar to *Help*.

So far, I have this:

;; Reuse old *eww* windows.
;; Otherwise, pop up a new window.
(setq-default display-buffer-alist
              (cons '("^\\*\\eww\\*$"

Is this method correct? I feel uneasy about the use of the use of regex to drive the behavior. Perhaps there is some other way of achieving the same result (e.g. using advice-add)?

  • I'm not sure exactly what behavior you're looking for. But maybe start by looking at C-h f with-help-window. That's what's generally used to create and show a help window. – Drew Dec 31 '20 at 23:40
  • @Drew I've actually looked at with-help-window, but my Emacs Lisp isn't great. – Flux Jan 1 at 0:04

As @Drew says, it's not clear what you're looking for. However, since I found your answer while creating my own function to reuse an eww window, I thought you might find it helpful.

It simply looks for a buffer called "*eww*" (the default name for eww). If there's a live window, then use that. Otherwise, call eww in the current window.

I've tried to document it fully. Remember, you can use C-h f, C-h v and C-h i d m elisp to learn more.

(defun my-lookup ()
  "Lookup symbol at point in PySide online documentation."
  ;; define function variables
  ;; let form defines variables, the * means you can use one definition within another
  (let* ((sym (thing-at-point 'symbol)) ; get symbol at point
         (url (concat
                      ))  ; define a web address using that symbol
         (buff (get-buffer-window "*eww*")))  ; check if there exists an eww buffer, get its window
    ;; begin function behavior
    (if buff
        (with-selected-window buff
          (eww url))  ; if eww buffer exists, call eww command in that window
      (eww url))))  ; otherwise call it in the current window

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