It seems the problem was caused by older user-base files repeairing some problems I had with older versions. 

I find the following problems:

(1) \starthiding-\stophiding is not functioning. Minimal example:
\starttext
\starthiding
CRY: 
\stophiding
Hello world.
\stoptext
Error message: ! Too many }'s.
\buff_stop #1->\egroup 
                       \getvalue {#1}
l.7 \stophiding

(2) This one is still not solved (2 problems in one):

\setuppapersize[A5]A5]
\definetextbackground[testA][%
location=text,background=color,backgroundcolor=yellow]
\starttext
\startitemize
\starttextbackground[testA]
\item \input tufte
\stoptextbackground
\stopitemize
\stoptext
(/Users/hans/TeX/context/tex/texmf-context/tex/context/sample/tufte.tex)
! Extra }, or forgotten \endgroup.
system          > tex > error on line 15 in file textbackground.tex: Extra }, or forgotten  ...
<inserted text> \egroup 
                        \hangindent 0.0pt\hangafter 1\parskip 0.0pt\leftskip...
\carryoverpar ...skip \rightskip \the \rightskip }                                                  
l.15 \stoptextbackground


And on interchanging the position of the textbackground it runs but the positioning is still wrong:
\item
\starttextbackground[testA]
\input tufte



Hans van der Meer



On 10 jan. 2012, at 14:38, Wolfgang Schuster wrote:


Am 10.01.2012 um 12:02 schrieb Hans van der Meer:

This is the error when installing the latest beta:

Works here:

mtx-context     | current version: 2012.01.09 10:08