Base plan, lockable, includes walls and rooms. Anything labelled as windows, doors or staircases are also automatically included in base plan (not movable).

Other furniture is by default not part of base plan. But you can control by checking/unchecking "Part of base plan" in the furniture dialogue.

I cannot remember whether it is possible to override the "part of base plan" (movable) for doors/windows/staircases with the FurnitureLibraryEditor,

ok