code: void reverse( Grid g ) {
  		work.clear();
  		int N = g.rows*g.columns;
  		for (int i = 0; i < N; i++) {
  			work.add( g.ellipses.get(N-i-1));
  		}
  
  		g.ellipses.clear();
  		g.ellipses.addAll(work);
  	}
docs: Reverse the order of elements inside the grid