Incompatibility with TikZ and Mac OS X Preview

Question

I was quite suprised to find that some TikZ documents render incorrectly under Preview (on Mac OS X), despite working fine in Adobe Reader (on Mac OS X) and Evince (on Linux). This is Mac OS X version 10.8.4.

The easiest way to reproduce this is with the custom pattern designs from this answer (see the custom north west lines example in the second code block). I will also reproduce the code below in case that answer is ever edited.

When I view the document in Preview on Mac OS X, this is what I see. Note in the third panel that the thick black lines do not go all the way to the edge of the box.

In Adobe Reader and Evince, I see the intended result:

My question is: is this a result of TikZ using some non-standard (or less well supported) feature of PDFs? Or is this a bug in Preview? (Note: even if this is a bug in Preview, if there is a workaround that is available on the TikZ side, that's probably much easier than trying to get Apple to fix it.)

I tried this in MacTeX (aka TeX Live) 2012 and 2013, and also TeX Live 2013 in Linux. I'm not sure exactly what version of TikZ is installed with those (I have done no customization of my installations).

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{patterns}

% defining the new dimensions and parameters
\newlength{\hatchspread}
\newlength{\hatchthickness}
\newlength{\hatchshift}
\newcommand{\hatchcolor}{}
% declaring the keys in tikz
\tikzset{hatchspread/.code={\setlength{\hatchspread}{#1}},
         hatchthickness/.code={\setlength{\hatchthickness}{#1}},
         hatchshift/.code={\setlength{\hatchshift}{#1}},% must be >= 0
         hatchcolor/.code={\renewcommand{\hatchcolor}{#1}}}
% setting the default values
\tikzset{hatchspread=3pt,
         hatchthickness=0.4pt,
         hatchshift=0pt,% must be >= 0
         hatchcolor=black}
% declaring the pattern
\pgfdeclarepatternformonly[\hatchspread,\hatchthickness,\hatchshift,\hatchcolor]% variables
   {custom north west lines}% name
   {\pgfqpoint{\dimexpr-2\hatchthickness}{\dimexpr-2\hatchthickness}}% lower left corner
   {\pgfqpoint{\dimexpr\hatchspread+2\hatchthickness}{\dimexpr\hatchspread+2\hatchthickness}}% upper right corner
   {\pgfqpoint{\dimexpr\hatchspread}{\dimexpr\hatchspread}}% tile size
   {% shape description
    \pgfsetlinewidth{\hatchthickness}
    \pgfpathmoveto{\pgfqpoint{0pt}{\dimexpr\hatchspread+\hatchshift}}
    \pgfpathlineto{\pgfqpoint{\dimexpr\hatchspread+0.15pt+\hatchshift}{-0.15pt}}
    \ifdim \hatchshift > 0pt
      \pgfpathmoveto{\pgfqpoint{0pt}{\hatchshift}}
      \pgfpathlineto{\pgfqpoint{\dimexpr0.15pt+\hatchshift}{-0.15pt}}
    \fi
    \pgfsetstrokecolor{\hatchcolor}
%    \pgfsetdash{{1pt}{1pt}}{0pt}% dashing cannot work correctly in all situation this way
    \pgfusepath{stroke}
   }

\begin{document}

\begin{center}
%
\begin{tikzpicture}
\draw[pattern=custom north west lines] (0,0) rectangle (3,4);
\end{tikzpicture}%
%
\begin{tikzpicture}
\draw[pattern=custom north west lines,hatchspread=6pt,hatchthickness=1pt,hatchcolor=red] (0,0) rectangle (3,4);
\end{tikzpicture}%
%
\begin{tikzpicture}
\draw[pattern=custom north west lines,hatchspread=10pt,hatchthickness=5pt] (0,0) rectangle (3,4);
\end{tikzpicture}%
%
\begin{tikzpicture}% hatchshift must be >= 0
\draw[pattern=custom north west lines,hatchspread=10pt,hatchcolor=red] (0,0) rectangle (3,4);
\draw[pattern=custom north west lines,hatchspread=10pt,hatchcolor=blue,hatchshift=2.5pt] (0,0) rectangle (3,4);
\draw[pattern=custom north west lines,hatchspread=10pt,hatchcolor=green!65!black,hatchshift=5pt] (0,0) rectangle (3,4);
\draw[pattern=custom north west lines,hatchspread=10pt,hatchcolor=violet,hatchshift=7.5pt] (0,0) rectangle (3,4);
\end{tikzpicture}%
%
\end{center}

\end{document}