[NTG-context] scaling metapost graphics

Matthew Huggett writes: Hello, let's start with #3

(3) With \useMPgraphic, is there any mechanism to scale the image as with \useexternalfigure?

\placefigure [right]{none}{\scale[sx=.6,sy=.6]{\useMPgraphic{....}}}

If this is all in the documentation, I apologize. (I would appreciate a pointer to the documentation though :-) )

it is somewhere I guess ;-) Patrick