onScrollStateChanged never get called

[wuketidai]

I set a OnScrollListener on StaggeredGrid, but the listener never get called. So i dive into source code and find that newState always equal to mTouchMode.

void reportScrollStateChange(int newState) {
        Log.d("staggeredGrid", "newState = " + newState + " mTouchMode = " + mTouchMode);
        if (newState != mTouchMode) {
            mTouchMode = newState;
            if (mOnScrollListener != null) {
                mOnScrollListener.onScrollStateChanged(this, newState);
            }
        }
    }