I  discovered  some problems  centring  a  float which  is
rotated using externalfigure.  Without rotation everything
is fine. However, when the orientation option is provided,
the  frame  doesn't match  the  figure  any more  and  the
centring gets  lost. Using the dedicated  rotation command
works. Example:

\starttext

\startbuffer [fig]
	\useMPlibrary [dum]
	\starttext
		\startTEXpage
			\externalfigure [placeholder] [width=10cm, height=4cm]
		\stopTEXpage
	\stoptext
\stopbuffer
\savebuffer [fig] [fig]
\executesystemcommand{context --purge \jobname-fig.tmp}

\startplacefigure [title={Centred, but not rotated}]
	\externalfigure [\jobname-fig]
\stopplacefigure

\page

\startplacefigure [title=Not centred and wrong frame location]
	\externalfigure [\jobname-fig] [orientation=90, frame=on]
\stopplacefigure

\page

\startplacefigure [title=Why is this one placed on the left?]
	\externalfigure [\jobname-fig] [orientation=89, frame=on]
\stopplacefigure

\page

\startplacefigure [title=Still not centred and wrong frame location]
	\midaligned{\externalfigure [\jobname-fig] [orientation=90, frame=on]}
\stopplacefigure

\page

\startplacefigure [title=This one works]
	\rotate[rotation=90]{\externalfigure [\jobname-fig]}
\stopplacefigure

\stoptext

Is this a bug?

Used version:
context 2011.11.29 23:11

Doesn't compile at all using:
context 2012.01.16 18:33

Marco