Long ago, I used XEmacs, and its buffer-local faces to highlight the active window and modeline. When I switched to Emacs, I was sad to see that it didn't have buffer-local and window-local faces. It does have a separate face for active and inactive modelines though.
Today I learned that Emacs 23 has a buffer-local face remapping feature. I'm using this to highlight the active buffer (not window):
;;; highlight-focus.el --- highlight the active buffer ;; Author: Amit J Patel <email@example.com> ;;; Commentary: ;; ;; I find that I'm not good at tracking when focus changes across ;; apps, windows, and within a window. As much as possible, I try to ;; have all my applications somehow draw attention to what has ;; focus. In X11 I marked the focus in red. In Firefox I marked the ;; text fields in yellow. This Emacs package highlights the active ;; buffer. It's inspired by an earlier package I had written for ;; XEmacs, which changes the window color and modeline color for the ;; current window. ;; ;;; History: ;; ;; 2013-05-10: Rewritten to use the Emacs 23 "remap faces" feature. ;; 2007-04-16: Initial version, temporarily highlighting the active buffer ;;; Code: (require 'face-remap) (defvar highlight-focus:last-buffer nil) (defvar highlight-focus:cookie nil) (defvar highlight-focus:background "white") (defun highlight-focus:check () "Check if focus has changed, and if so, update remapping." (unless (eq highlight-focus:last-buffer (current-buffer)) (when (and highlight-focus:last-buffer highlight-focus:cookie) (with-current-buffer highlight-focus:last-buffer (face-remap-remove-relative highlight-focus:cookie))) (setq highlight-focus:last-buffer (current-buffer) highlight-focus:cookie (face-remap-add-relative 'default :background highlight-focus:background)))) (defadvice other-window (after highlight-focus activate) (highlight-focus:check)) (defadvice select-window (after highlight-focus activate) (highlight-focus:check)) (defadvice select-frame (after highlight-focus activate) (highlight-focus:check)) (add-hook 'window-configuration-change-hook 'highlight-focus:check) (provide 'highlight-focus) ;;; highlight-focus.el ends here
There's some more tweaking I need to do but so far it seems to be working reasonably well.