[NTG-context] itemize and vertical spacing

[Olivier]

Dear all,

To put vertical space in an itemized construction is easy via

\startitemize[inbetween={\blank[30pt]}]
\item first
% a 30pt vertical space will be inserted here
\item second
% a 30pt vertical space will be inserted here
\item third
% a 30pt vertical space will be inserted here
\item fourth
\stopitemize


But, now assume I want to typeset the list in two columns:
\startitemize[inbetween={\blank[30pt]}]
\item first 
\item second
\item third
\item fourth
\stopitemize

the vertical space is discarded, whereas I would like to get the
following result
\startitemize[inbetween={\blank[30pt]}]
\item first 
\item second
% a 30pt vertical space will be inserted here
\item third
\item fourth
\stopitemize

Is there a way to achieve this?

Thanks,
Olivier