Is it possible to set fill-colour (or not fill at all) when showing a .map-files, or are you stuck with the shaded interior?
Topic on Help talk:Extension:Kartographer
The .map file can have colors. Here is an example: commons:Data:Bulgaria/149SUSchoolSector.map. Mixing properties when the data source in a .map file is currently not possible. There is an ongoing discussion if this should change, see phab:T323559.
Thanks for the advice!