grid.setOnScrollListener(object: AbsListView.OnScrollListener {

            var mLastVisibleItem: Int = 0

            override fun onScrollStateChanged(view: AbsListView?, scrollState: Int) {}

            override fun onScroll(view: AbsListView, firstVisibleItem: Int, visibleItemCount: Int, totalItemCount: Int) {
                val currentFirstVisibleItem = grid.getFirstVisiblePosition()

                if(currentFirstVisibleItem > mLastVisibleItem)
                    getSupportActionBar().hide()
                else if(currentFirstVisibleItem < mLastVisibleItem)
                    getSupportActionBar().show()

                mLastVisibleItem = currentFirstVisibleItem

            }
        })