* Helm
#+NAME: helm
#+BEGIN_SRC emacs-lisp
  (use-package helm
    :ensure t
    :config
    (defun my-helm-display-frame-center (buffer &optional resume)
      "Display `helm-buffer' in a separate frame which centered in parent frame."
      (if (not (display-graphic-p))
	  ;; Fallback to default when frames are not usable.
	  (helm-default-display-buffer buffer)
	(setq helm--buffer-in-new-frame-p t)
	(let* ((parent (selected-frame))
	       (frame-pos (frame-position parent))
	       (parent-left (car frame-pos))
	       (parent-top (cdr frame-pos))
	       (width (/ (frame-width parent) 2))
	       (height (/ (frame-height parent) 3))
	       tab-bar-mode
	       (default-frame-alist
		 (if resume
		     (buffer-local-value 'helm--last-frame-parameters
					 (get-buffer buffer))
		   `((parent . ,parent)
		     (width . ,width)
		     (height . ,height)
		     (undecorated . ,helm-use-undecorated-frame-option)
		     (left-fringe . 0)
		     (right-fringe . 0)
		     (tool-bar-lines . 0)
		     (line-spacing . 0)
		     (desktop-dont-save . t)
		     (no-special-glyphs . t)
		     (inhibit-double-buffering . t)
		     (tool-bar-lines . 0)
		     (left . ,(+ parent-left (/ (* (frame-char-width parent) (frame-width parent)) 4)))
		     (top . ,(+ parent-top (/ (* (frame-char-width parent) (frame-height parent)) 6)))
		     (title . "Helm")
		     (vertical-scroll-bars . nil)
		     (menu-bar-lines . 0)
		     (fullscreen . nil)
		     (visible . ,(null helm-display-buffer-reuse-frame))
		     ;; (internal-border-width . ,(if IS-MAC 1 0))
		     )))
	       display-buffer-alist)
	  (set-face-background 'internal-border (face-foreground 'default))
	  (helm-display-buffer-popup-frame buffer default-frame-alist))
	(helm-log-run-hook 'helm-window-configuration-hook)))

    (setq helm-display-function 'my-helm-display-frame-center)
    (helm-mode)
    :bind (("M-x" . helm-M-x)
	   ("C-x r b" . helm-filtered-bookmarks)
	   ("C-x C-f" . helm-find-files)
	   ("C-x b" . helm-buffers-list)))
#+END_SRC