The auto-dim-other-buffers-mode is a global minor mode which makes
windows without focus less prominent. With many windows in a frame,
the idea is that this mode helps recognise which is the selected
window by providing a non-intrusive but still noticeable visual
indicator.
The preferred way to install the mode is by grabbing
auto-dim-other-buffers package form MELPA:
M-x package-install RET auto-dim-other-buffers RET
Once installed, the mode can be turned on (globally) with:
M-x auto-dim-other-buffers-mode RET
To make the mode enabled every time Emacs starts, add the following to
Emacs initialisation file (~/.emacs or ~/.emacs.d/init.el):
(add-hook 'after-init-hook (lambda ()
(when (fboundp 'auto-dim-other-buffers-mode)
(auto-dim-other-buffers-mode t))))
To configure how dimmed buffers look like, customise
auto-dim-other-buffers-face. This can be accomplished by:
M-x customize-face RET auto-dim-other-buffers-face RET
More customisation can be found in auto-dim-other-buffers
customisation group which can be accessed with:
M-x customize-group RET auto-dim-other-buffers RET
Note that despite it’s name, since Emacs 27 the mode operates on windows rather than buffers. I.e. selected window is highlighted and all other windows are dimmed even if they display the same buffer.