Highlight selected window by adjusting contrast of text
 "foreground" and background.
Working good if you switch themes frequently, contrast will be kept.
Also this works for modeline.
We also highligh cursor position, this may be disabled with
 (setopt selected-window-contrast-region-flag nil) in .emacs
 or
 M-x customize-variable RET selected-window-contrast-region-flag

;; Usage:

(add-to-list 'load-path "path_to/selected-window-contrast") ; optional
(when (require 'selected-window-contrast nil 'noerror)
  (setopt selected-window-contrast-bg-selected 0.95)
  (setopt selected-window-contrast-bg-others 0.75)
  (setopt selected-window-contrast-text-selected 0.9)
  (setopt selected-window-contrast-text-others 0.6)
  (add-hook 'buffer-list-update-hook
            #'selected-window-contrast-highlight-selected-window))

;;  How this works:

 1) We get color with `face-attribute' `selected-frame' for
 foreground and backgraound.
 2) Convert color to HSL
 3) adjust brightness in direction of foreground-background average
 4) convert color to RGB, then to HEX
 5) apply color

Customize: M-x customize-group RET selected-window-contrast

Note, if you use C-o to switch windows, this may conflict with
 rectangle-mark-mode-map
Rebind keys then:
(keymap-set rectangle-mark-mode-map "C-c o" #'open-rectangle)
(keymap-set rectangle-mark-mode-map "C-o" #'other-window)

;; Donate:

- BTC (Bitcoin) address: 1CcDWSQ2vgqv5LxZuWaHGW52B9fkT5io25
- USDT (Tether TRX-TRON) address: TVoXfYMkVYLnQZV3mGZ6GvmumuBfGsZzsN
- TON (Telegram) address: UQC8rjJFCHQkfdp7KmCkTZCb5dGzLFYe2TzsiZpfsnyTFt9D

;; Other packages:

- Modern navigation in major modes https://github.com/Anoncheg1/firstly-search
- Search with Chinese	https://github.com/Anoncheg1/pinyin-isearch
- Ediff no 3-th window	https://github.com/Anoncheg1/ediffnw
- Dired history		https://github.com/Anoncheg1/dired-hist
- Copy link to clipboard	https://github.com/Anoncheg1/emacs-org-links
- Solution for "callback hell"	https://github.com/Anoncheg1/emacs-async1
- Restore buffer state	https://github.com/Anoncheg1/emacs-unmodified-buffer1
- outline.el usage		https://github.com/Anoncheg1/emacs-outline-it
- Call LLMs & AIfrom Org-mode block.  https://github.com/Anoncheg1/emacs-oai