Selection should be implemented by UI components with children which are exposed by
atk_object_ref_child and get_n_children, if the use of the
parent UI component ordinarily involves selection of one or more of the objects corresponding to those
Object children - for example, selectable lists.
Note that other types of "selection" (for instance text selection) are accomplished a other ATK interfaces -
Selection is limited to the selection/deselection of children.
Determines if the current child of this object is selected Note:
callers should not rely on null or on a zero value for indication of whether AtkSelectionIface is implemented, they
should use type checking/interface checking macros or the atk_get_accessible_value convenience method.