Why does other-window-for-scrolling ignores variable other-window-scroll-buffer?

Question

According to the documentation of other-window-for-scrolling we should be able to specify the "other window" by setting the variable other-window-scroll-buffer:

other-window-for-scrolling is a built-in function in ‘src/window.c’.

(other-window-for-scrolling)

Return the other window for "other window scroll" commands. If in the minibuffer, ‘minibuffer-scroll-window’ if non-nil specifies the window. Otherwise, if ‘other-window-scroll-buffer’ is non-nil, a window showing that buffer is used, popping the buffer up if necessary. Finally, look for a neighboring window on the selected frame, followed by all visible frames on the current terminal.

However, in reality this seems to be ignored:

(setq other-window-scroll-buffer "*R*")

(other-window-for-scrolling) --> #<window 558 on header.html>

Is this a bug or feature that was removed?

Answer 1

The doc for other-window-scroll-buffer says:

If this is a live buffer, C-M-v should scroll its window.

(emphasis added). IOW, the value must be a buffer, not the name of a buffer. So try:

(setq other-window-scroll-buffer (get-buffer "*R*"))

get-buffer is a function that returns a buffer, given its name (a string). If no such buffer exists, it returns nil. See its doc string with C-h f get-buffer.