It appears that the behaviour of RGFGRID with multiple polygons as
shown in this video by Dano is not present anymore in its latest
iteration (I'm using the 2019.1 release, 5.05.00.59437): https://www.youtube.com/watch?v=aBFH1vWCO90&t=
I'm not sure when this disappeared but in the RGFGRID version coming
with Delft3D 4.02.03 it works as in the video. In the 2019.1 version
it either makes just a grid in the island polygon or covers it with a
How are islands supposed to be dealt with 'nowadays'?