Just before going to bed, I've found a solution with all your help and the help of Taco Hoekwater through the ntg mail archive :

\def\startSlide%
{\def\stopSlide{\checkSlide\doif{\getvariable{temp}{publish}}{yes}{\page\getbuffer[Slide]}}%
\dostartbuffer[Slide][startSlide][stopSlide]}

Let me know if it's my philosopher's stone...
I've tried it and it works so far.

No more ugly gobbling, my mind is free.

So depressing problem and so simple and elegant solution...

On 07 Nov 2014, at 16:17, Hans Hagen <pragma@wxs.nl> wrote:

On 11/7/2014 2:26 PM, Pierre-François Bonnefoi wrote:
Hello Hans,

thank you for contributing to solve my problem.

I've tried your proposition : how can I get the content of the buffer
afterward ?
I've tried \getbuffer[Slide] with no success on MKIV beta that I've just
updated.

\starttext

\definebuffer[Slide]

foo

\startSlide
bla bla bla
\starttyping
language C code
\stoptyping
bla bla bla
\stopSlide

bar

\getbuffer[\thedefinedbuffer{Slide}]

\getSlide

\stoptext


Does a buffer work only for verbatim content ?

no, for everything

best regards,
Pierre-François.

On 07 Nov 2014, at 12:38, Hans Hagen <pragma@wxs.nl
<mailto:pragma@wxs.nl>> wrote:


\starttext

\definebuffer[Slide]

foo

% \skipSlide
\startSlide
bla bla bla
\startyping
language C code
\stoptyping
bla bla bla
\stopSlide

bar

\stoptext



--
Bonnefoi Pierre-Francois                |    E-mail : bonnefoi@unilim.fr
<mailto:bonnefoi@unilim.fr> http://libpfb.so/
Universite de Limoges, Laboratoire XLIM |       Tel : 06 28 18 03 38
123 av Albert Thomas                    |  Mrs. Peel, we're needed...
87060 Limoges CEDEX - FRANCE            |                 The Avengers.



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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________

-- 
Bonnefoi Pierre-Francois                |    E-mail : bonnefoi@unilim.fr http://libpfb.so/
Universite de Limoges, Laboratoire XLIM |       Tel : 06 28 18 03 38
123 av Albert Thomas                    |  Mrs. Peel, we're needed...
87060 Limoges CEDEX - FRANCE            |                 The Avengers.