message: Fix incorrect display offset after rotation
  Regression was introduced in
  however it was working before only due to grid.len() bug.
diff: @@ -523,7 +523,7 @@ impl<T: GridCell + PartialEq + Copy> Grid<T> {
  if region.start == Line(0) {
  // Update display offset when not pinned to active area
  if self.display_offset != 0 {
  - self.display_offset = min(self.display_offset + *positions, self.len() - num_lines);
  + self.display_offset = min(self.display_offset + *positions, self.max_scroll_limit);
  }
  self.increase_scroll_limit(*positions, template);
  