MapProjectionDisplay question

[Stuart Maclean <stuart@xxxxxxxxxxxxxxxxxx>]

I am trying to use the IDV classes to build navigated displays.  I learnt the whole 'display side coordinate system' technique 
from MapProjectionDisplay.java in the visad/examples.  In particular, how a call to MapProjection.setDefaultMapArea with a xy 
rectangle would result in the visad 'box' showing the xy area.

When moving to the higher level idv classes, I thought the corresponding call was in 
ucar.unidata.view.geoloc.MapProjectionDisplay.setMapArea ( ProjectionRect).  This does not seem to do what I want.  I did peek 
at the source code and noted that the comments for that method imply that the rectangle is in fact a lat/lon rectangle, not a 
cartesian one.

Can anyone shed any light on the setMapArea (and setMapRegion) methods, and how 
to use them correctly?

Thanks

Stuart