when current line is the first line of current window(lines_above = 0), the value of show_at is still cur_line - 1, it should be changed to cur_line. and new code is compatible with the old code which is when current line is the first line of buffer, show_at = 0. #241
when current line is the first line of current window(lines_above = 0), the value of show_at is still cur_line - 1, it should be changed to cur_line. and new code is compatible with the old code which is when current line is the first line of buffer, show_at = 0. #241