If you have LabVIEW 6.1 or higher, you can use the Event Structure to capture the click of the 'X' button, and choose to ignore it and close the panel.
Configure an Event Case to "This VI..Panel Close?" filter event. (note the question mark) On the right side of this new case, there will be a boolean terminal that will let you discard the event. Open a reference to the VIT and pass this out of the main loop, and use a property node on this reference to close the front panel, then close the reference.
It will go away when you hit the 'X' without prompting to save.
A simple example is attached. You'll either need ot make a change or copy everything to a new VI and run that to prove it doesn't prompt for saving changes. This is in 7.1, Let me know if you need it in an earlier version.
Ed
Message Edited by Ed Dickens on 03-03-2005 12:58 PM