Would like to tell me how to show history line in picture for Hobbit ?

list Yong Tang
Tue, 3 Jun 2008 11:26:42 +0800
Message-Id: <user-0ebc9324129d@xymon.invalid>

Hello!
   Hobbit is a good tool software for monitoring servers, applications and
networks, very much!
   Would like to tell me how to show history line in picture?
   Thank You very much!

Tang Yong
2008-06-03