Caption issue with tufte-latex and ctable

When using ctable with the tufte-latex class (in xelatex), I get an error when defining a caption (and hence a label).

! Undefined control sequence. \@tufte@stored@caption ->\@ctblcaptionarg**

Anybody knows a way to correctly place a caption and a label, maybe using the doinside option of ctable? It's not possible to enclose ctable in another float.

Here's a small example:

\documentclass[nols,nofonts]{tufte-handout}

\usepackage{textcomp}
\usepackage{fontspec}

\usepackage{ctable}
\usepackage{pdflscape}

\begin{document}

\ctable[pos = Htbp,
left,
caption = thisisacaption,
label = thisisalabel
]{lrcr}
{% notes
}
{% rows
\FL
\parbox[b]{0.41\columnwidth}{\raggedright
\emph{This}
} & \parbox[b]{0.20\columnwidth}{\raggedleft
\emph{Is}
} & \parbox[b]{0.20\columnwidth}{\centering
\emph{An}
} & \parbox[b]{0.18\columnwidth}{\raggedleft
\emph{Example}
}
\LL
}

\end{document}

-

If you'd like to use the ctable-style captions (as opposed to the Tufte-style captions), then you can add the following block of code to the preamble of your document (just prior to the \begin{document} line):

% Disable Tufte-style captions for ctables
\makeatletter % allows @ in macro names
\def\@ctblCaption{
\ifx\@ctblcap\undefined\let\@ctblcap\@ctblcaption\fi
\ifx\@ctblcaption\empty\else
\gdef\@ctblcaptionarg{\ifx\@ctbllabel\empty\else\label{\@ctbllabel}\fi
\@ctblcaption\ \@ctblcontinued\strut}
\ifx\@ctblcap\empty
\caption[]{\@ctblcaptionarg}
\else
\caption[\@ctblcap]{\@ctblcaptionarg}
\fi
\fi
}
\makeatother % restores original meaning of @

-
Kevin, fantastic, thank you so much. It'd be great if you could write also how to use the Tufte-style captions, but this solves it more than acceptably. Thanks again. –  Roberto Jan 9 '12 at 5:30
@Roberto: I've updated the code to use Tufte-style captions. Should the table notes appear below the table (as they currently do) or as part of the caption or a separate sidenote? –  godbyk Jan 17 '12 at 8:14
Kevin, I think notes below the table are fantastic. Thanks again! –  Roberto Jan 17 '12 at 16:26
@godbyk: Please see tex.stackexchange.com/questions/57396/… –  Marco Daniel May 26 '12 at 9:21