+You get a window which looks like the one in figure
+\ref{bbi-fig-bbi-gui}
+(the exact appearance of \bbi is system and \bbtk version dependent)
+\footnote{If you compiled \bbtk without \wx then \bbi does not have a
+graphical interface but a simple prompt}.
+
+\begin{figure}[!ht]
+\caption{\label{bbi-fig-bbi-gui}The black box interpreter interface}
+\begin{center}
+\includegraphics[width=0.7\textwidth]{bbi-gui.png}
+\end{center}
+\end{figure}
+
+The 'Command' tab is subdivided into two parts :
+one single line zone at the bottom in which you can enter your commands and
+one multiple line zone in which \bbi prints out the result of your commands.