Problem with \tkzClipSector and bounding box in tkz-euclide

Question

Here's a problem I can't solve. As you can see in the figure below, the clip is bounded by the sector, but the bounding box is modified. I can get around this problem easily, but I'd like to find out what's causing it.

Here are some possible workarounds:

1) \tkzClipBB
    \tkzClipSector(O,A)(C)
    \tkzDrawLines[ultra thick](O,B A,C)

2) \tkzClipSector(O,A)(C)
   \tkzClipCircle(O,A)
   \tkzDrawLines[ultra thick](O,B A,C)

3) \pgfinterruptboundingbox
   \tkzClipSector(O,A)(C)
   \tkzDrawLines[ultra thick](O,B A,C)
   \endpgfinterruptboundingbox

\documentclass{standalone}
\usepackage{tkz-euclide}
\begin{document}
  
\begin{tikzpicture}
\tkzDefPoints{0/0/O,2/0/A,0/6/B,-2/0/C}
\tkzDrawPoints(O,A,C)
\tkzDrawCircle(O,A)
\tkzClipSector(O,A)(C)
\tkzDrawLines[ultra thick](O,B A,C)
\end{tikzpicture}
\end{document}

Note that if, instead of drawing a straight line, I fill in a disk, the problem is identical:

\fbox{\begin{tikzpicture}
\tkzDefPoints{0/0/O,2/0/A,0/6/B,-2/0/C}
\tkzDrawPoints(O,A,C)
\tkzDrawCircle(O,A)
\tkzClipSector(O,A)(B)
\tkzFillCircle[red](O,B)
\end{tikzpicture}}

Last remark: no problem if I clip a circle.

\fbox{\begin{tikzpicture}
\tkzDefPoints{0/0/O,2/0/A,0/6/B,-2/0/C}
\tkzDrawPoints(O,A,C)
\tkzDrawCircle(O,A)
\tkzClipCircle(O,A)
\tkzDrawLines[ultra thick](O,B A,C)
\end{tikzpicture}}

You can find the macros for sector layouts here : tkz-obj-eu-sectors.tex. I tried to find out from these macros when the bounding box could be modified, but without success!

Do you have an explanation for this problem?

Answer 1

What I think I understood: The clip inserted between begingroup and endgroup limits the draws but not the bounding box.

Without clip

With clip and without begingroup

With clip and begingroup

CODE

    \documentclass{standalone}
    \usepackage{tikz}
    \begin{document}

    \fbox{%
    \begin{tikzpicture}
    \node (O) at(0,0){$O$};
    \node (A) at(2,0){$A$};
    \node (B) at(0,6){$B$};
    \node (C) at(-2,0){$C$};
    % \begingroup
    % \clip[draw](O) -- (0:2) arc(0:180:2) -- cycle;
    % \endgroup
    \draw(O)--(B)--+(0,1);
    \node (D) at (0,10){D};
    \end{tikzpicture}
    }


    \fbox{%
    \begin{tikzpicture}
    \node (O) at(0,0){$O$};
    \node (A) at(2,0){$A$};
    \node (B) at(0,6){$B$};
    \node (C) at(-2,0){$C$};
    % \begingroup
    \clip[draw](O) -- (0:2) arc(0:180:2) -- cycle;
    % \endgroup
    \draw(O)--(B)--+(0,1);
    \node (D) at (0,10){D};
    \end{tikzpicture}
    }

    \fbox{%
    \begin{tikzpicture}
    \node (O) at(0,0){$O$};
    \node (A) at(2,0){$A$};
    \node (B) at(0,6){$B$};
    \node (C) at(-2,0){$C$};
    \begingroup
    \clip[draw](O) -- (0:2) arc(0:180:2) -- cycle;
    \endgroup
    \draw(O)--(B)--+(0,1);
    \node (D) at (0,10){D};
    \end{tikzpicture}
    }
    \end{document}