Well I downloaded the latest version and still...

xx = SendMessage(Text1.hWnd, EM_LINESCROLL, 0, 1)

scrolls to the end, not just one line!

There's no panic as I got round the problem by using Sendkey and the down arrow to scroll the number of lines I wanted. However, it would be nice to know if TextBoxW responds incorrectly to an EM_LINESCROLL message or whether I am doing something wrong!