TikZ: transparency causes problems with the color black (opacity, transparency, color model, Adobe Reader)

Question

I want to have a fill color with transparency but I also want the text to be perfectly opaque. But somehow it does not work.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes,}

\begin{document}

\begin{tikzpicture}[myStack/.style={
  rectangle split, 
  rectangle split parts=3, 
  draw, 
  fill=yellow,
  fill opacity = 0.6,
  text=black,
  text opacity = 1,
  }]

\node [myStack]{
                abc
\nodepart{two}  bde
\nodepart{three}cfg
};
\end{tikzpicture}

\end{document}

When I zoom in (Adobe Reader) then I also see that even the black border is not really black and rather dark gray.

Can somebody reproduce the problem?

Update

After I updated MiKTeX the problem was kind of solved. However black still is rather dark gray. After opening the PDF with Adobe Professional I figured out that when I change the color profile then black is black again. See the screenshots (in German):

Problem: Black is gray

Problem solved:

Can anyone reproduce that black is not black?

PS: I think it's related to this question.

Problem Solved

Apparently this and this questions address the same problem. Adding

\pdfpageattr{/Group <</S /Transparency /I true /CS /DeviceRGB>>}

before \begin{document} solved the problem. According to Martin Heller "this makes Adobe Reader use the RGB rendering model for pages with transparency". Still I don't get it fully...

Answer 1

Fillopacity will affect the text, if you want a "transparent" color, and a black text do yellow!60 instead.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shapes,}

\begin{document}

\begin{tikzpicture}[myStack/.style={
  rectangle split, 
  rectangle split parts=3, 
  draw, 
  fill=yellow!60,
  %fill opacity = 0.6,
  }]

\node [myStack]{
                abc
\nodepart{two}  bde
\nodepart{three}cfg
};
\end{tikzpicture}

\end{document}