NULL or on a zero value for
indication of whether AtkSelectionIface is implemented, they should
use type checking/interface checking functions or the
atkGetAccessibleValue() convenience method.atkSelectionRefSelection(object, i)objectAtkSelection]  a GObject instance that implements AtkSelectionIfaceiinteger specifying the index in the selection set.  (e.g. the
ith selection as opposed to the ith child).