On 2013–10–10 Xan wrote:

> with this code:
> 
> 
> % Paràbola amb Focus = (0,0.25) i Directriu (x,-0.25)
> \placefigure[here]
> [taula:construcció-paràbola-1]
> {Paràbola amb directriu $r$ i focus $F$}
> {\framed[frame=off]{
> \starttikzpicture[domain=(-1):1, scale=4, smooth,decoration={
>   markings,% switch on markings
>   mark=% actually add a mark
>   between positions 0 and 1 step 0.5
>   with
>   {
>    \draw[color=gray] (0,-2pt) -- (0,2pt);
>   }
> }]
> \coordinate (F) at (0,0.25);
> \draw[very thick] (-2.2,-0.25) -- (2.2,-0.25) node[right] {$r$};
> \draw[color=blue, very thick] plot (\x,{(\x)^2});
> 
> \foreach \x in {1,0.5,0.75}
> {
>    \draw[very thick,color=green, loosely dashed,postaction={decorate}] (\x, -0.25) -- (\x , {(\x)^2});
>    \draw[very thick,color=green, loosely dashed,postaction={decorate}] (\x , {(\x)^2}) -- (F);
> }
> \filldraw[color=red] (F) circle (0.5pt);
> \draw (F) node[anchor=north] {$F$};
> \stoptikzpicture}}
> 
> 
> 
> this happens when I updated to the latest version:
> $ sh ./first-setup.sh --context=beta --modules=all --engine=luatex
> 
> What happens there?

Hard to tell. Please provide a minimal example next time. I tried to
condense your example, but I'm getting a different error than you
do. Maybe I deleted too much or my syntax is invalid. I don't really
know TikZ.

\usemodule [tikz]
\usetikzlibrary [decorations]

\starttext
  \starttikzpicture
    [decoration={
       mark= between positions 0 and 1 step 0.5
       with { \draw (0,-2pt) -- (0,2pt);}}]
    \draw node {foo};
  \stoptikzpicture
\stoptext

Marco