Hi Don, many thanks for the speedy reply.
I build a Mercator projection, and set its defaultMapArea with a ProjectionRect (cartesian values, i.e. projected from the
lat,lon). I then construct a MapProjectionDisplay and call setMapProjection.
I have got it all working. This was actually a sort of red herring. I wasn't seeing any Displayables show up, and I was
erroneously assuming that my projection logic was wrong. So I looked at the main method in the MapProjectionDisplay (was a life
saver, thanks for including it!). I wasn't ever calling the 'draw' method, doh!