> Meer, Hans van der <mailto:H.vanderMeer@uva.nl>
> 24. Mai 2016 um 15:04
>
> Can someone explain to me the changes in fontsize in the following 
> example?
> Enclosing the fontswitches in a group did not change the behaviour.
>
> \setupbodyfont[dejavu,12pt]
> \def\MarkMasterA{\inmargin[location=left]{\bgroup\switchtobodyfont[9pt]\red 
> Master\egroup}}
> \def\MarkMasterB{\inmargin[location=left]{\bgroup\usebodyfont[9pt]\red 
> Master\egroup}}
> \starttext
> \startsection[title=\MarkMasterA First title]
> \input hawking
> \MarkMasterA
> \input hawking
> \stopsection
> \startsection[title=\MarkMasterB First title]
> \input hawking
> \MarkMasterB
> \input hawking
> \blank
> contextversion=\contextversion
> \stopsection
> \stoptext
>
> In the first section the absolute value of 9 pt appears not to be 
> honoured but it looks as if there is a reduction relative to the 
> surrounding font.
> In the second section the size does not change and looks even bigger 
> than the first one above.
>
> I am baffled and do not understand why not all fontsizes are the same 
> absolute 9pt as requested?
When you flush the margin text in the heading its style (e.g. \tfa) is 
added to your font size for the margin text.

To get rid of the size change from \section in your example you can add 
the "reset" keyword to \switchtobodyfont.

\def\MarkMasterA{\margindata[inleft][style={\switchtobodyfont[reset,9pt]},color=red]{Master}}

Wolfgang