Gets the number of accessible children currently 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.
| this |
a Object instance that implements AtkSelectionIface |
|
a gint representing the number of items selected, or 0 if this does not implement this interface. |