Lock gummi preview pane to main file

I got a latex document for which I want to outsource the different chapters

+folder
| main.tex
| first.tex
| second.tex


I am using gummi as an editor. Now I got the problem or rather inconvenience that as soon as I start editing in another file than main.tex, gummi is not showing the current document status in the preview pane anymore as only main.tex is an actual completely legal latex document and the other files are only included sub parts and can therefore not be compiled.

\begin{document}
\include{./first}
\include{./second}
\end{document}


Can I configure the preview pane in a way that (for a certain project/session) that only a certain file will be compiled and shown in the preview pane?

I finally solved the problem indirectly by introducing macros to cover for generating valid latex code in the subfiles.

The main.tex file defines \def\COMPLETE{} whereas any included file now has in the beginning

\ifdefined\COMPLETE
\else
\documentclass[12pt]{article}
\input{util} %file containing all the used libraries
\begin{document}
\fi


and

\ifdefined\COMPLETE
\else
\end{document}
\fi


at the end. Therefore if the file is not included in the main, but displayed on its own it still has the necessary code to be valid.