Hi ichang,
This link deals with this issue as well:
http://community.sagemas.com/t5/Distribution-Manufacturing-and/Comment-Fields-in-Business-Framework-...
There is a .dll file that needs also to go to the workstation.
Also, when modifying a comment you need to press the insertkey to expand the cell with the text and then use the up and down cursor keys.
Hope this helps.
Elliott
