The property is a [structGLib.Variant] property to specify where and
what kind of white spaces to draw.
The [structGLib.Variant] is of type "au", an array of unsigned integers. Each
integer is a combination of [flagsSpaceTypeFlags]. There is one
integer for each [flagsSpaceLocationFlags], in the same order as
they are defined in the enum (%GTK_SOURCE_SPACE_LOCATION_NONE and
%GTK_SOURCE_SPACE_LOCATION_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 %GTK_SOURCE_SPACE_TYPE_NONE.
By default, %GTK_SOURCE_SPACE_TYPE_ALL is set for all locations.4
Whether the [property
SpaceDrawer:matrix] property is enabled.