Emacs Sr-speedbar

;; speedbar
(require 'sr-speedbar)
(setq sr-speedbar-width 20)           ; width
(setq sr-speedbar-max-width 20)
(setq sr-speedbar-right-side nil)     ; put it to the left
(setq speedbar-show-unknown-files t)  ; show all files
(sr-speedbar-open)
(with-current-buffer sr-speedbar-buffer-name
  (setq window-size-fixed 'width))  ; keep width after resize window