Thank for the schemas. It seems good to me. We still have the issue of
coordinate system type. In the current schema, CS are declared as
integer (probably EPSG code). We way wish to accept arbitrary
[CS_]CoordinateSystem object in a future version.
About the widget schema, my main question is: where exactly do we want
to put zoom functionality? In current schema, it is a separated tools.
In my mind, I tend to treat zoom as a special case and put this tool
right into MapPane. My rational is that is is pratically impossible to
renderer a map without some kind of zoom (or scaling). Maps always have
some scale like 1:50000. To me, this is a kind of zoom (coordinates
points has to be zoomed out by a factor of 50000). Zooming a map is
basically just changing its scale. On an implementation note, it seem to
me that a zoom tool doesn't bring new functionalities to MapPane...