Thanks for the suggestion Alan!

I tried out the pagecolumns approach.  According to the manual it seems to
handle floats a bit better than the columnsets and I do not require spans right
now.  However, here another weird thing is happening.  After the end of the
pagecolumns an extra page is flushed even though it does not contain any
material.  Why?  MWE is below, output of latest beta attached.

Cheers, Henri

---

\setuppapersize[A0]
\setupbodyfont[sans,25pt]

\definepagecolumns
  [threecolumn]
  [n=3]

\setuppagecolumns
  [threecolumn]
  [distance=3cm]

\starttext

\startpagecolumns[threecolumn]

  \input lorem

\column

  \input zapf\par

  \startplacefigure[title={\input zapf\par}]
    \externalfigure[dummy][width=\columnwidth]
  \stopplacefigure

  \input hawking\par

\column

  \input Douglas\par

  \input bryson\par

  \startplacefigure[title={\input bryson\par}]
    \externalfigure[dummy][width=\columnwidth]
  \stopplacefigure

\stoppagecolumns

\stoptext

On Mon, 2018-04-16 at 19:08 -0600, Alan Braslau wrote:
> Hans points out that you need to use:
> \setuplayout [grid=yes]
> with columnsets (and floats).
> 
> You can also try "pagecolumns", yet another mechanism, each has its own
> charm. ;-)
> 
> Alan
> 
> 
> 
> 
> On Tue, 17 Apr 2018 12:59:46 +1200
> Henri Menke <henrimenke@gmail.com> wrote:
> 
> > 
> > Dear list,
> > 
> > I wanted to make a conference poster in ConTeXt MKIV using the
> > newcolumnsets. However, when I use floats weird shit is happening.
> >  Is this intended or am I doing something seriously wrong?  MWE
> > below, output of latest beta attached.
> > 
> > Cheers, Henri
> > 
> > ---
> > 
> > \setuppapersize[A0]
> > \setupbodyfont[sans,25pt]
> > 
> > \usemodule[newcolumnsets]
> > 
> > \definecolumnset
> >   [threecolumn]
> >   [n=3]
> > 
> > \setupcolumnset
> >   [threecolumn]
> >   [distance=3cm]
> > 
> > \starttext
> > 
> > \startcolumnset[threecolumn]
> > 
> >   \input lorem
> > 
> > \column
> > 
> >   \input zapf\par
> > 
> >   \startplacefigure[title={\input zapf\par}]
> >     \externalfigure[dummy][width=\textwidth]
> >   \stopplacefigure
> > 
> >   \input hawking\par
> > 
> > \column
> > 
> >   \input Douglas\par
> > 
> >   \input bryson\par
> > 
> >   \startplacefigure[title={\input bryson\par}]
> >     \externalfigure[dummy][width=\textwidth]
> >   \stopplacefigure
> > 
> > \stopcolumnset
> > 
> > \stoptext