Variable: window--sides-shown
window--sides-shown is a buffer-local variable defined in
window.el.gz.
Documentation
Non-nil if this buffer was shown in a side window once.
If this variable is non-nil in a buffer, switch-to-prev-buffer
and switch-to-next-buffer will refrain from showing this buffer
within the main window area. display-buffer-in-side-window
sets this variable automatically.
Killing buffer local variables after showing the buffer in a side window annihilates any effect provided by this variable.
Source Code
;; Defined in /usr/src/emacs/lisp/window.el.gz
(defvar-local window--sides-shown nil
"Non-nil if this buffer was shown in a side window once.
If this variable is non-nil in a buffer, `switch-to-prev-buffer'
and `switch-to-next-buffer' will refrain from showing this buffer
within the main window area. `display-buffer-in-side-window'
sets this variable automatically.
Killing buffer local variables after showing the buffer in a side
window annihilates any effect provided by this variable.")