\input{preamble-standalone.ltx}
\begin{document}

% Ex. No. 85 (Section 10.5.1 : Example of the use of \tkzcname{tkzRestoreBB})

\begin{tikzpicture}
 \tkzDefPoint(-2,-2){A}
 \tkzDefPoint(2,1){B}
 \tkzDefPoint(0,0){O}
 \tkzSaveBB
 \tkzShowBB[red,line width=1pt]
 \tkzRestoreBB
 \tkzDrawCircle(O,B)
 \tkzClipBB
 \tkzFillCircle[gray!20](O,B)
\end{tikzpicture}

\end{document}