I am following the current tutorial (MWE) : link
However, I am facing difficulties to perform a tree of 4 nodes. Items are superposed, and even if I add a child [missing] {} it doesn't solve the issue.
On below an example of code which is not displayed correctly :
\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{trees}
\begin{document}
\tikzstyle{every node}=[draw=black,thick,anchor=west]
\tikzstyle{selected}=[draw=red,fill=red!30]
\tikzstyle{optional}=[dashed,fill=gray!50]
\begin{tikzpicture}[%
grow via three points={one child at (0.5,-0.7) and
two children at (0.5,-0.7) and (0.5,-1.4)},
edge from parent path={(\tikzparentnode.south) |- (\tikzchildnode.west)}]
\node {texmf}
child { node {doc}}
child { node {fonts}}
child { node {source}}
child { node [selected] {tex}
child { node {generic}}
child {
node [optional] {latex}
child { node {latex21} }
child { node {latex22} }
child { node {latex23} }
}
child [missing] {}
child [missing] {}
child [missing] {}
child {
node {plain}
child { node {plain21} }
child { node {plain22} }
child { node {plain23} }
}
child [missing] {}
child [missing] {}
child [missing] {}
}
child [missing] {}
child [missing] {}
child [missing] {}
child [missing] {}
child [missing] {}
child [missing] {}
child { node {texdoc}};
\end{tikzpicture}
\end{document}

Actually, I do not understand where and when to use child [missing] {}. Thank you in advance for your help.

dirtreepackage, which doesn't usetikz: How to draw a hierarchical structure with edges?. For an alternative tree input syntax, (much easier) you can also usetikz-qtree. See Horizontal hierarchy tree in tikz-qtree: bad layout for longer node-names for an example like yours. – Alan Munn Jul 25 '13 at 15:15