Current questions and answers regarding the map editor.

This option in MapProperties doesn't seem to work for some reason, based on my observations. You need to go into MapPropertiesTree (the map properties tree, the panel on the left, enabled by the button of the same name at the top). In this tree, you need the "GroundAmbientLights" item for the surface and "UndergroundAmbientLights" for the dungeon. Add one element to the list and then work with that element. You can create a new one (the "New" button) or take one from the existing ones (the "..." button).