Agent Only Callback Campaign Lock - not locking campaign_id

Greetings, we are using a recent svn build VERSION: 2.2.0-183 BUILD: 90511-0910 where we had paid for this requested feature.
It works great and has the desired behavior except for one minor problem.
When an agent enters the manual callbacks, dispositions it again as a callback it rewrites the campaign_id field to the currently logged in campaign.
Is it a trivial matter to keep this field locked once its been set in a particular campaign?
It works great and has the desired behavior except for one minor problem.
When an agent enters the manual callbacks, dispositions it again as a callback it rewrites the campaign_id field to the currently logged in campaign.
Is it a trivial matter to keep this field locked once its been set in a particular campaign?