As title says, let lua access map thumbnail and minimap patches because thats the only way that those can be accessed by lua.
mapheaderinfo[map].thumbnail
gives the map thumbnail patch and mapheaderinfo[map].minimap
gives the minimap patch. If for some reasons those arent loaded or valid then loads "BLANKLVL" youfuckedup patch as a failsafe
results using simple lua coding to display maps thumbnails and minimaps on screen.