Doing an /rline causes to window to scroll to currently selected line. The following example creates a window with 1000 lines and updates line 300 once every three seconds. Try scrolling the window by dragging the scrollbar or by mousewheel, and you'll notice how it always jumps back to the currently selected line (line 10 in this case) when the timer runs.
Code:
alias scrolltest {
  window -lar @scroll
  var %i = 1
  while (%i <= 1000) {
    aline @scroll line %i
    inc %i
  }
  sline @scroll 10
  timer 10 3 rline @scroll 300 line replaced
}


This is very annoying, I have script that continuously updates a window that can have up to 5000 lines, with anything from 0 to 200 updates per minute. Needles to say trying to scroll with a mousewheel/scrollbar is completely useless because this problem. As a workaround you can (pretty much have to at the moment) move in the window with Arrows and PageUp/Down, but it sure would be great if this was fixed.