I have two problems with figures placed into the left or right margin. When the figure is in a group, extra whitespace is inserted between the paragraphs that precede and follow the placefigure command. This happens for figures placed by startplacefigure/stopplacefigure and tradiitonal placefigure commands, and paragraphs placed by startparagraph/stopparagraph or marked by par or newlines.

When the figure is not in a group, whitespace called for by \setupwhitespace is lost, except when the paragraphs are marked by traditional means. That is, whitespace is lost when startparagraph/stopparagraph is used.

Interestingly, when that is changed to bpar/epar, the problem for ungrouped figures disappears, but as I understand it, bpar/epar is not a real substitute for startparagraph/stopparagraph.

There is probably a simple explanation, but it eludes me. I prefer to be able to use startparagraph/stopparagraph, and it is sometimes desirable to place a figure into a group in order to prevent unique settings from leaking out.

The following should demonstrate the problem. Turning on grid setting makes it worse. I get the same result with current betas and older versions.

\useMPlibrary   [dum]
%\showgrid
\setuplayout    [%grid=yes,
                 backspace=151pt,leftmargin=117pt]
\setupwhitespace[big]
\define\Paragraph{\startparagraph\input khatt-en\stopparagraph}
\starttext
{
\subject{Start/stop paragraphs and figures}
\subsubject{Group, extra whitespace}
\Paragraph
\Paragraph
\begingroup
    \startplacefigure[location={leftmargin,none}]
      \externalfigure[A]
    \stopplacefigure
\endgroup
\Paragraph
\Paragraph
\subsubject{No group, no whitespace}
\Paragraph
\Paragraph
\startplacefigure[location={leftmargin,none}]
    \externalfigure[A]
\stopplacefigure
\Paragraph
\Paragraph
\Paragraph
}
\page
{
\subject{Start/stop paragraphs, traditional figures}
\subsubject{Group, extra whitespace}
\Paragraph
\Paragraph
{\placefigure[leftmargin,none]{}{\externalfigure[A]}}
\Paragraph
\Paragraph
\subsubject{No group, no whitespace}
\Paragraph
\Paragraph
\placefigure[leftmargin,none]{}{\externalfigure[A]}
\Paragraph
\Paragraph
\Paragraph
}
\page
{
\subject{Traditional paragraphs, start/stop figures}
\subsubject{Group, extra whitespace}
\input khatt-en\par
\input khatt-en\par
\begingroup% or \bgroup or {
    \startplacefigure[location={leftmargin,none}]
      \externalfigure[A]
    \stopplacefigure
\endgroup% or \egroup or }
\input khatt-en\par
\input khatt-en\par
\subsubject{Okay}
\input khatt-en\par
\input khatt-en\par
\startplacefigure[location={leftmargin,none}]
    \externalfigure[A]
\stopplacefigure
\input khatt-en\par
\input khatt-en\par
\input khatt-en\par
}
\page
{
\subject{Traditional paragraphs, traditional figures}
\subsubject{Group, extra whitespace}
\input khatt-en\par
\input khatt-en\par
{\placefigure[leftmargin,none]{}{\externalfigure[A]}}
\input khatt-en\par
\input khatt-en\par
\subsubject{Okay}
\input khatt-en\par
\input khatt-en\par
\placefigure[leftmargin,none]{}{\externalfigure[A]}
\input khatt-en\par
\input khatt-en\par
\input khatt-en\par
}
\stoptext

--
Rik