diskselector_example_02: Added 'selected' callback usage.

This reveals the diskselector bug that the GUI is not updated even after
the selected item is changed.
Click "Delete item" button to test it.

legacy/elementary/src/examples/diskselector_example_02.c

@@ -13,6 +13,14 @@
 
 static int counter = 3;
 
+static void
+_ds_selected_cb(void *data EINA_UNUSED, Evas_Object *obj EINA_UNUSED,
+                void *event_info)
+{
+   Elm_Object_Item *it = event_info;
+   printf("Selected Item %s\n", elm_object_item_text_get(it));
+}
+
 static void
 _add_cb(void *data, Evas_Object *obj, void *event_info)
 {
@@ -200,6 +208,7 @@ elm_main(int argc, char **argv)
    ds = elm_diskselector_add(win);
    evas_object_size_hint_weight_set(ds, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
    evas_object_size_hint_align_set(ds, EVAS_HINT_FILL, EVAS_HINT_FILL);
+   evas_object_smart_callback_add(ds, "selected", _ds_selected_cb, NULL);
    elm_box_pack_end(bx, ds);
    evas_object_show(ds);