kml GroundOverlay/ScreenOverlay support

Hi all,
I’m doing some tests with the Kml branch.

When I load a kml containing a GroundOverlay, I get an exception.

In the debugger, I think the problem is related to this line :

entity.position = new ConstantPositionProperty(Ellipsoid.WGS84.cartographicToCartesian(Rectangle.getCenter(extent, scratchCartesian), scratchCartographic));

Rectangle.getCenter is undefined (no trace of it in Rectangle.js) but there is a center function. Probably something renamed.

… well after examining the end of the function, it seems that GroundOverlay support is not yet implemented.

I have to improve kml support in Cesium and the actual kml branch looks as a very good starting point.

I’am wondering what are the best solutions to implement GroundOverlay and ScreenOverlay support regarding what is already available in Cesium.

Any help appreciated.