On Tue, 12 Jul 2016, Hans Hagen wrote:

> On 7/12/2016 3:44 PM, Henri Menke wrote:
>> Dear Hans,
>>
>> thanks for your reply.  Indeed there are color definitions in
>> `pgfutil-context.def`.  However, they are commented out with the message
>>
>>> % no need for x colors (users can load it if needed)
>>> ...
>>> %\pgfutil@definecolor{gray}{gray}{0.5}
>>
>> If I add
>>
>>> \csname pgfutil@definecolor\endcsname{gray}{gray}{0.5}
>>
>> to my document the gray shows up fine.  So that's for sure a feasible
>> workaround.
>>
>> Can you comment on the phrase »no need for x colors (users can load it
>> if needed)«?  I'm not quite sure what it means and it suggests that
>> there exists a proper solution to my color problem.
>
> normally you want the same colors in tikz images as in context so then 
> defining them in tikz is creating incompatibilities (your case is the 
> reverse and a-typical)

However, without such redefinitions, tikz does not understand ConTeXt 
colors. I use a similar workaround in my documents as well.

Perhaps, one could define a macro `\enabletikzcolors[...list..]` that will 
do the appropriate translations.

Aditya