I would suggest to try to calculate the length of the custom fields in JIRA. For example, if you view the descriptions of links for the below issue, http://jira.atlassian.com/browse/CONF-6992, you see that the descriptions are limited to 40 characters only even though there is a lengthy blank gap between the description and the icons for priority.
I personally would like to see the full description of the links instead of them being cut off after a hard-coded 40 character length?