[NTG-context] transparent metafun colors turn nearly black

[Sanjoy Mahajan]

>> (I wonder if the live context has been having the same problem?)

> I tried to fix it after Taco reported the exact problem. Plese test
> if it's working now.

Thanks, the live context works!  I tested this file:

  \setupcolors[state=start]
  \starttext
  \startreusableMPgraphic{a}
  fill fullcircle scaled 10cm withcolor transparent(1,0.5,green) ;
  \stopreusableMPgraphic

  \placefigure[force,none]{}{\reuseMPgraphic{a}}
  \stoptext

and a nice transparent green circle shows up.

I also tested (overlapping transparent squares):

  \setupcolors[state=start]
  \starttext
  \startreusableMPgraphic{a}
  fill unitsquare scaled 1cm withcolor yellow;
  fill unitsquare shifted (0.5,0.5)
    scaled 1cm withcolor transparent(1,0.5,red);
  \stopreusableMPgraphic

  \placefigure[force,none]{}{\reuseMPgraphic{a}}
  \stoptext

and it now works.

-Sanjoy

`Never underestimate the evil of which men of power are capable.'
         --Bertrand Russell, _War Crimes in Vietnam_, chapter 1.