/// of \param os. If \param shorten is true, then we will shorten
/// \param os to maxlen chars and replace the final three by "...,
/// if \param os is longer than maxlen chars.
+ /// if \param maxlen is passed as 0, then it is ignored. (In fact,
+ /// it is reset to the maximum value for size_t.)
void forToc(docstring & os, size_t maxlen, bool shorten = true) const;
/// insert a character at cursor position