Method showPrev

example/uxsampletest.cpp:39–45

  }

  void showPrev() {
      if (mResourceList.empty()) return;
      mCurIndex--;
      if (mCurIndex < 0)
          mCurIndex = mResourceList.size() - 1;
      show();
  }

  void showNext() {
    if (mResourceList.empty()) return;