I'm not sure of the best way to handle this and I understand the problem. What I would look into doing is some sort of information saving during the screen entry. Every few seconds save the info from it. Either that or change the timeout to something over 20 minutes. I don't think you're going to be able to trap the timeout message for the workstation.
If you want to expand your question to many more eyes, I would post it at Midrange.com in the Midrange-L mailing list. I'm sure you'll get quite a few other ideas from there.
Sorry I couldn't be of more help. This one just isn't my forte these days. :)
The problem lies with one particular program that gives the user a large field for entry. They typically type long, verbose entries into this field (or set of 10 fields I should say) on a screen. The user doesn't do anything to reset the inactivity timer during this period of time and then the system ends their session for inactivity. all the data typed in the fields on that screen is lost.
Changing the timeout length is not an option unfortunately.
I shall also post this on Midrange, and have been trying to post to Code400 as well.
Hope that helps clear up any ambiguity about the issue at hand. Thanks.