This is my code, which doesn't work:
\documentclass{article}
\usepackage{tikz}
\begin{document}
\tikz \node {start\linebreak{}stop};
\end{document}
The \linebreak command doesn't work. In order to make it working I have to say \node[text width=5em]... Is there any other method to make it working, without explicit specification of the node text width?

\nodepart, I just want to use\linebreak. I have many lines in the node, much more than\nodepartallows (up to 4). – yegor256 Jul 20 '10 at 14:30