Variable: window-sides-vertical
window-sides-vertical is a customizable variable defined in
window.el.gz.
Value
nil
Documentation
If non-nil, left and right side windows occupy full frame height.
If nil, top and bottom side windows occupy full frame width.
This variable was added, or its default value changed, in Emacs 26.1.
Source Code
;; Defined in /usr/src/emacs/lisp/window.el.gz
;; Side windows.
(defcustom window-sides-vertical nil
"If non-nil, left and right side windows occupy full frame height.
If nil, top and bottom side windows occupy full frame width."
:type 'boolean
:initialize 'custom-initialize-default
:set 'window--sides-verticalize
:group 'windows
:version "26.1")