GZDoom Builder will automatically load data from (Z)MAPINFO lump if it's present in map resources. Both new and old MAPINFO definition styles are supported.
Several values from (Z)MAPINFO are used in Visual mode. List of supported properties:
fade;
outsidefog;
fogdensity;
outsidefogdensity;
vertwallshade;
horizwallshade;
evenlighting;
smoothlighting.
You can reload (Z)MAPINFO by using "Reload (Z)MAPINFO" action.