(Potential) new feature for Org-mode: "hidden-lines cookies"

[Thorsten Jolitz <tjolitz@gmail.com>]

Hi List, 

I implemented a new (optional and customizable) feature for
'outshine.el' (https://github.com/tj64/outshine):

,--------------------------------------------------------------------
| Behind every folded headline, a little 'cookie' shows the number of
| hidden lines till the next visible headline.
`--------------------------------------------------------------------

E.g., an Emacs Lisp buffer structured the 'outshine-way', with
'outline-minor-mode' and 'outshine' activated, might look like this
after doing 'M-x outshine-show-hidden-lines-cookies':

,-------------------------------------------------------------------------------
| ;; * navi-mode.el --- major-mode for easy buffer-navigation [#13]
| ;; ** Commentary [#1]
| ;; *** About navi-mode
| 
| ;; This file implements extensions for occur-mode. You can think of a
| ;; navi-buffer as a kind of 'remote-control' for an (adecuately)
| ;; outline-structured original-buffer. It enables quick navigation and basic
| ;; structure editing in the original-buffer without (necessarily) leaving the
| ;; navi-buffer. When switching to the original-buffer and coming back after
| ;; some modifications, the navi-buffer is always reverted (thus up-to-date).
| 
| ;; Besides the fundamental outline-heading-searches (8 outline-levels) and the
| ;; 5 basic keyword-searches (:FUN, :VAR, :DB, :OBJ and :ALL), all languages
| ;; can have their own set of searches and keybindings (see `navi-key-mappings'
| ;; and `navi-keywords'). Heading-searches and keyword-searches can be
| ;; combined, offering a vast amount of possible 'views' at the
| ;; original-buffer.
| 
| ;; *** Usage [#165]
| ;; *** Installation [#19]
| ;; *** Emacs Version [#5]
| ;; * Requires [#4]
| ;; * Mode Definitions [#30]
`-------------------------------------------------------------------------------

 'M-x outshine-hide-hidden-lines-cookies' deletes all the cookies again. 

Now I wonder if such a feature already exists in Org-mode (I would not
be surprised, but I'm not aware of it) and if anybody would be
interested in having such a feature?

I guess it would be quite easy to extract the relevant functionality
from outshine.el and make it a contrib library for Org-mode (mostly
renaming of definitions and maybe replacing some outline-functions by
their Org-mode equivalents. 

On the other hand - this is new (customizable) syntax, and with the new
parser and exporting framework there are probably more things to
consider than just porting the code to an Org-mode library.

PS 
Note that the appearance of the cookies can actually be completely
customized by 4 customizable variables that define 'left/right
delimiter' and 'left/right signal char'.

-- 
cheers,
Thorsten