forest combines bunch of single grass straws and after use that bunch for scattering grass
the spline area affect the whole bunches
as a result I still have grass over curb or blank gaps near the curb
any way to fix it? or include this in the new features
(scattering single straws would be a very huge number of instances)
Did you try setting Areas->Boundary Checking to "Size" ? In the current version this feature works only with Area Splines, not directly with a Surface Area. For the next update, it will be available for both modes.
Please, see also my previous post about the Grass Edges