[NTG-context] pagecolumns: get the current column

[mf]

Hello list,
I'm using a 2-columns layout and I'd like to put some information in the 
margin.
I should put that information in the left margin when I'm in the left 
column, and in the right margin when I'm in the right column, to prevent 
the extra information overlapping the main text in the other column.

I found a useful counter in page-pcl.mkiv: \c_page_col_current.

Here's a MWE:

\unprotect
\def\curCol{\c_page_col_current}
\protect

\def\InfoInMargin#1{\doifelse{\the\curCol}{1}{\inmargin{#1}}{\inothermargin{#1}}}
\def\TestText{\InfoInMargin{\bf \the\curCol}\input ward 
\InfoInMargin{\bf \the\curCol} \input ward}
\starttext
   \startpagecolumns[n=2,distance=25mm]
   \dorecurse{5}{\TestText\par}
   \stoppagecolumns
\stoptext

\c_page_col_current works most of the time, but unfortunately it tells 
you the current column before the lines of a paragraph get distributed 
over columns.

So sometimes it fails. You can see that in the MWE: the bold "1" between 
columns in the upper part of the page. It should be a bold "2" in the 
right margin.

Is there a better way to read the current column?

Thanks,
Massi