Polygon Objects (as well as other similar Objects) are defined in the simulator by adding a number of points which are connected by the simulator to form the polygon.
If the Terraforming option is chosen, it is possible to define a Fall-off Distance, which is the distance around the polygon over which the altitude distance between the polygon (set through the Gizmo) and the surrounding terrain is smoothed.
Additional functionality would allow the Gizmo be used at each polygon defining point to set the point's altitude, rather than just the polygon in general.
Also, why cannot the Fall-off Distance be defined for each polygon defining point, rather than just in general for the polygon as a whole?
These changes would allow sloping polygons as well as differing Fall-off Distances on the various polygon sides.