Dear all, I am a newbie in ConTeXt. I am accustomed to use pgf in LaTeX and
have seen that pgf is also a module for ConTeXt. When using some of my pgf
macros in ConTeXt, I had several erros coming from the fact that colors are
defined by the "same" command in both pgf and ConTeXt, namely
\definecolor[mycolor][r=,g=,b=] in ConText and
\definecolor{mycolor}{rgb}{,,} in pgf.
It seems to me impossible to use the pgf command directly and, in the same
time, impossible to use ConTeXt-defined color in pgf macros.
Here is an example :
\usemodule[pgf]
\definecolor[mycolor][r=0.5,g=0.5,b=0.5]
\starttext
\pgfdeclarehorizontalshading{myshading}{1cm}{%
  color(0cm)=(mycolor);color(1cm)=(green)}
\pgfuseshading{myshading}
\stoptext

There is an error with \definecolor and the shading. If you replace
(mycolor) by (red) in the shading and suppress the \definecolor, it is fine.
Best regards.