Thanks a lot Mr Emura for adding this!
Oh, and in order to make it as flexible as possible, i.e. in order to e.g. please the opinions mentioned in this thread, I could suggest to make the number of locked rows configurable, or perhaps even more simple than that, do what I suggested above already, i.e. simply add the boolean option to synchronize the side-scrolling of split windows, and people could then split however they like and achieve this themselves, just like you originally suggested in this thread?