docs: public boolean performItemClick(int position) {
          if (isShowing()) {
              if (mItemClickListener != null) {
                  final DropDownListView list = mDropDownList;
                  final View child = list.getChildAt(position - list.getFirstVisiblePosition());
                  final ListAdapter adapter = list.getAdapter();
                  mItemClickListener.onItemClick(list, child, position, adapter.getItemId(position));
              }
              return true;
          }
          return false;
      }