[ 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 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 NONE.
By default, ALL is set for all locations.