what kind of white spaces to draw.
The #GVariant is of type "au", an array of unsigned integers. Each integer is a combination of #GtkSourceSpaceTypeFlags. There is one integer for each #GtkSourceSpaceLocationFlags, in the same order as they are defined in the enum ([gtksource.types.SpaceLocationFlags.None] and [gtksource.types.SpaceLocationFlags.All] are not taken into account).
If the array is shorter than the number of locations, then the value for the missing locations will be [gtksource.types.SpaceTypeFlags.None].
By default, [gtksource.types.SpaceTypeFlags.All] is set for all locations.