Once Stuart has committed the latest version of the merge request, we can start porting the hard-coded "MapWidget" dialog soon, and probably the NavDisplay afterwards - that means, there'll be another handful of "map layers". The process to use the MVC-oriented approach is documented at: http://wiki.flightgear.org/Canvas_Map_API
Alfo and Jomo (developers of ATC-FS) will probably re-use these layers then to port ATC-FS to the Canvas.
Note that we'll probably want to further improve the MVC design, because the "controller" part doesn't exist at the moment...