- \item wxWindows library (optional)
- \par Used for platform-independent graphical interface. The graphical-shell
- program \ctsim\ requires this library.
- \par www.wxwindows.org
-\end{itemize}
+ \item \textbf{libpng}\\
+ Used for PNG file export.\\
+ \urlref{Web site}{http://www.libpng.org/pub/png/libpng.html}
+
+ \item \textbf{zlib}\\
+ Used for PNG file export.\\
+ \urlref{Web site}{http://www.info-zip.org/pub/infozip/zlib/zlib_docs.html}
+
+ \item \textbf{readline}\\
+ Used for \ctsimtext\ interactive shell.\\
+ \urlref{Web site}{http://www.gnu.org}