[ Version ( since = "3.24" ) ]
public Variant matrix { owned get; set construct; }
The matrix property is a Variant property to specify where and what kind of white spaces to draw.
The Variant is of type `"au"`, an array of unsigned integers. Each integer is a combination of SourceSpaceTypeFlags. There is one integer for each SourceSpaceLocationFlags, 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.