Avoiding blank line in every node (tikzpicture)

Question

I created a box using

\tikzstyle{PBox}=[rectangle, rounded corners, fill=kopfzeile!10, 
  anchor=north, text=black, text width=\marginparwidth-2mm]
\put(-56,-150){\makebox(0,0)[bl]{\begin{tikzpicture}%
 \node[PBox]{\small%
 \singlespacing%
 Wichtiger Hinweis!\\};
\end{tikzpicture}}}

I always get a blank line at the start of each PBox. How can I avoid this?

Answer 1

You could set the single spacing in another way to avoid the blank line, use \setstretch{1} instead of \singlespace:

\documentclass{article}
\usepackage[doublespacing]{setspace}
\usepackage{tikz}
\tikzstyle{PBox}=[rectangle, rounded corners, fill=kopfzeile!10, 
  anchor=north, text=black, text width=\marginparwidth-2mm]
\begin{document}
\begin{picture}(20,20)
\put(-56,-150){\makebox(0,0)[bl]{\begin{tikzpicture}%
  \node[PBox]{\small%
    \setstretch{1}%
    Wichtiger Hinweis!\\};
\end{tikzpicture}}}
\end{picture}
\end{document}

The reason is, that \singlespacing makes a vertical skip of one line, as you can see in the definition:

\newcommand{\singlespacing}{%
  \setstretch {\setspace@singlespace}%  normally 1
  \vskip \baselineskip  % Correction for coming into singlespace
}

Output:

Answer 2

First, It's preferable to post a complete compilable MWE. Secondly, you need to use an figure environment and you need to place \singlespacingoutsside the node

 \documentclass[11pt]{article}
 \usepackage{xcolor,tikz}
 \usepackage{setspace}

 \begin{document}
 \tikzstyle{PBox}=[rectangle, rounded corners, fill=blue!10, 
                  anchor=north, text=black, text width=\marginparwidth-2mm] 
 \singlespacing   
 \setlength\unitlength{1mm}  
 \begin{picture}(0,0)   
   \put(-51,-150){\makebox(0,0)[bl]{%
   \begin{tikzpicture} 
      \node[PBox] {\small Wichtiger Hinweis!\\};
   \end{tikzpicture} 
}%
}%     
\end{picture}  

\end{document}