Dear Kevin,

On 25.05.2010, at 08:23, Kevin Rodgers wrote:

> Stefan Vollmar wrote:
>> Hallo,
>> I want to re-define what happends when an exising toolbar icon is
>> pressed. In the Emacs documentation I found an example similar to
>> this:
>> (define-key   global-map   [tool-bar new-file]
>>  '(menu-item "New Buffer" my-new-buffer
>> 			  :image (image :type xpm :file "new.xpm")))
> > Executing this code in Emacs 23.2 this will indeed show the desired
> > effect - but only for about 2 seconds: the tool-bar is then
> > automatically redrawn and behaves as before. How can I modify an
> > existing toolbar so that the change is persistent?
> 
> -- Variable: tool-bar-map
>     By default, the global map binds `[tool-bar]' as follows:
>          (global-set-key [tool-bar]
>          		'(menu-item "tool bar" ignore
>          			    :filter (lambda (ignore) tool-bar-map)))
>     Thus the tool bar map is derived dynamically from the value of
>     variable `tool-bar-map' and you should normally adjust the default
>     (global) tool bar by changing that map.  Major modes may replace
>     the global bar completely by making `tool-bar-map' buffer-local
>     and set to a keymap containing only the desired items.  Info mode
>     provides an example.


I looked up how changing the toolbar is done in info.el and was able to solve my problem with this code:

(defvar my-tool-bar-map tool-bar-map)
(define-key my-tool-bar-map [new-file] 
  '(menu-item "New Document (Org)" my-new-buffer
			  :image (image :type xpm :file "new.xpm")))
(set (make-local-variable 'tool-bar-map) my-tool-bar-map)

The "New File" icon (left-most in Emacs 23.2) will now use my own function (a wrapper for Kevin Rodger's switch-to-new-untitled-buffer code, thanks!), which is

(defun my-new-buffer ()
  "creates an empty new 'untitled' buffer"			
  (interactive)
  (put 'buffer-offer-save 'permanent-local t)
  (let ((default-major-mode 'org-mode)) 
	(switch-to-new-untitled-buffer)))

Thanks again, Kevin!

Warm regards,
 Stefan
-- 
Dr. Stefan Vollmar, Dipl.-Phys.
Head of IT group
Max-Planck-Institut für neurologische Forschung
Gleuelerstr. 50, 50931 Köln, Germany
Tel.: +49-221-4726-213  FAX +49-221-4726-298
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Email: vollmar@nf.mpg.de   http://www.nf.mpg.de