update emacs config to 21th century

conf-lisp/narrow.el

@@ -0,0 +1,22 @@
+;; *** narrowing (no mode but fits here)
+
+;; I use narrowing quite frequently, so here are some enhancements.
+
+;; easier narrowing with Indirect Buffers
+;; Source: [[https://www.emacswiki.org/emacs/NarrowIndirect3][emacswiki]]
+(require 'narrow-indirect)
+(defalias 'nf 'ni-narrow-to-defun-indirect-other-window)
+(defalias 'nr 'ni-narrow-to-region-indirect-other-window)
+
+;; I  like to  have  an  orange fringe  background  when narrowing  is
+;; active, since I forget that it is in effect otherwise sometimes.
+
+;; via [[https://emacs.stackexchange.com/questions/33288/how-to-find-out-if-narrow-to-region-has-been-called-within-save-restriction][stackoverflow]]
+(defun tvd-narrowed-fringe-status ()
+  "Make the fringe background reflect the buffer's narrowing status."
+  (set-face-attribute
+   'fringe nil :background (if (buffer-narrowed-p)
+                               tvd-fringe-narrow-bg
+                             nil)))
+
+(add-hook 'post-command-hook 'tvd-narrowed-fringe-status)