# sequence diagram problem with text layout/spacing/line-breaks?

I am currently trying to use a tikz-uml sequence diagram for some script and have the following code:

    \begin{tikzpicture}[scale=\textwidth/15.2cm,samples=200]
\tikzumlset{fill object = white, fill call = gray!20}
\tikzstyle{every node}=[font=\small]

\begin{umlseqdiag}
\umlactor[no ddots]{User}
\umlobject[no ddots]{User Agent}
\umlobject[no ddots]{Service Provider}
\umlobject[no ddots]{Identity Provider}

\begin{umlcall}[dt=8, op={Access Service}, return={Success}]{User}{User Agent}

\begin{umlcall}[dt=8, op={Browser Requests Resource}, return={302 Redirect to IdP}]{User Agent}{Service Provider}
\end{umlcall}

\begin{umlcall}[dt=8, op={Browser Requests SAML Token}, return={401 Authenticate}]{User Agent}{Identity Provider}
\end{umlcall}

\begin{umlcall}[dt=8, op={Authentication via Kerberos/NTLM/Login-Form}, return={SAML Token}]{User Agent}{Identity Provider}
\end{umlcall}

\begin{umlcall}[dt=8, op={Browser Requests Resource with SAML2 Token}, return={200 OK}]{User Agent}{Service Provider}
\end{umlcall}

\end{umlcall}
\end{umlseqdiag}
\end{tikzpicture}



When used within my latex document this reduces the following output:

I now do have a couple of problems with this output:

• The text rendering looks bad, is there a chance to make the messages multi-line texts? For example it would be nice to add a new line after "Requests" in "Browser Requests SAML Token"
• I didn't find a way of adding more spacing between the initial call and the answer documents. For example "Browser Requests Resource" and "302 Redirect to IdP" are way to tight to each other.

thanks, Andreas

• Welcome to TeX.SE! Please -- as usual here -- make your code snippet compilable, then we do not have to guess, what you are doing ... – Mensch Apr 12 at 7:44
• You can use \shortstack{a\\b} as in tex.stackexchange.com/questions/288590/… – Torbjørn T. Apr 13 at 7:48
• I tried that with \begin{umlcall}[dt=8, op={\shortstack{Browser Requests \\Resource}}, return={\shortstack{302\\Redirect to IdP}}]{User Agent}{Service Provider}. But this just yielded a Use of \@shortstack doesn't match its definition – Andreas Happe Apr 13 at 9:43